2023
Marini, Andrea
Equilibrium and out-of-equilibrium realistic phonon self-energy free from overscreening Journal Article
In: Phys. Rev. B, vol. 107, iss. 2, 2023.
Links | BibTeX | Tag: General Engineering
@article{Marini2023,
title = {Equilibrium and out-of-equilibrium realistic phonon self-energy free from overscreening},
author = {Andrea Marini},
url = {http://doi.org/10.1103/PhysRevB.107.024305},
doi = {10.1103/PhysRevB.107.024305},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
journal = {Phys. Rev. B},
volume = {107},
issue = {2},
keywords = {General Engineering},
pubstate = {published},
tppubtype = {article}
}
Smejkal, Valerie; Trovatello, Chiara; Li, Qiuyang; Conte, Stefano Dal; Marini, Andrea; Zhu, Xiaoyang; Cerullo, Giulio; Libisch, Florian
Photonic effects in the non-equilibrium optical response of two-dimensional semiconductors Journal Article
In: Opt. Express, vol. 31, no 1, 2023, ISSN: 1094-4087.
Abstract | Links | BibTeX | Tag: and Optics, Atomic and Molecular Physics
@article{Smejkal2022,
title = {Photonic effects in the non-equilibrium optical response of two-dimensional semiconductors},
author = {Valerie Smejkal and Chiara Trovatello and Qiuyang Li and Stefano Dal Conte and Andrea Marini and Xiaoyang Zhu and Giulio Cerullo and Florian Libisch},
doi = {10.1364/oe.479518},
issn = {1094-4087},
year = {2023},
date = {2023-00-00},
journal = {Opt. Express},
volume = {31},
number = {1},
publisher = {Optica Publishing Group},
abstract = {<jats:p>Transient absorption spectroscopy is a powerful tool to monitor the out-of-equilibrium optical response of photoexcited semiconductors. When this method is applied to two-dimensional semiconductors deposited on different substrates, the excited state optical properties are inferred from the pump-induced changes in the transmission/reflection of the probe, <jats:italic>i.e.</jats:italic>, Δ<jats:italic>T</jats:italic>/<jats:italic>T</jats:italic> or Δ<jats:italic>R</jats:italic>/<jats:italic>R</jats:italic>. Transient optical spectra are often interpreted as the manifestation of the intrinsic optical response of the monolayer, including effects such as the reduction of the exciton oscillator strength, electron-phonon coupling or many-body interactions like bandgap renormalization, trion or biexciton formation. Here we scrutinize the assumption that one can determine the non-equilibrium optical response of the TMD without accounting for the substrate used in the experiment. We systematically investigate the effect of the substrate on the broadband transient optical response of monolayer MoS<jats:sub>2</jats:sub> (1L-MoS<jats:sub>2</jats:sub>) by measuring Δ<jats:italic>T</jats:italic>/<jats:italic>T</jats:italic> and Δ<jats:italic>R</jats:italic>/<jats:italic>R</jats:italic> with different excitation photon energies. Employing the boundary conditions given by the Fresnel equations, we analyze the transient transmission/reflection spectra across the main excitonic resonances of 1L-MoS<jats:sub>2</jats:sub>. We show that pure interference effects induced by the different substrates explain the substantial differences (<jats:italic>i.e.</jats:italic>, intensity, peak energy and exciton linewidth) observed in the transient spectra of the same monolayer. We thus demonstrate that the substrate strongly affects the magnitude of the exciton energy shift and the change of the oscillator strength in the transient optical spectra. By highlighting the key role played by the substrate, our results set the stage for a unified interpretation of the transient response of optoelectronic devices based on a broad class of TMDs.</jats:p>},
keywords = {and Optics, Atomic and Molecular Physics},
pubstate = {published},
tppubtype = {article}
}
<jats:p>Transient absorption spectroscopy is a powerful tool to monitor the out-of-equilibrium optical response of photoexcited semiconductors. When this method is applied to two-dimensional semiconductors deposited on different substrates, the excited state optical properties are inferred from the pump-induced changes in the transmission/reflection of the probe, <jats:italic>i.e.</jats:italic>, Δ<jats:italic>T</jats:italic>/<jats:italic>T</jats:italic> or Δ<jats:italic>R</jats:italic>/<jats:italic>R</jats:italic>. Transient optical spectra are often interpreted as the manifestation of the intrinsic optical response of the monolayer, including effects such as the reduction of the exciton oscillator strength, electron-phonon coupling or many-body interactions like bandgap renormalization, trion or biexciton formation. Here we scrutinize the assumption that one can determine the non-equilibrium optical response of the TMD without accounting for the substrate used in the experiment. We systematically investigate the effect of the substrate on the broadband transient optical response of monolayer MoS<jats:sub>2</jats:sub> (1L-MoS<jats:sub>2</jats:sub>) by measuring Δ<jats:italic>T</jats:italic>/<jats:italic>T</jats:italic> and Δ<jats:italic>R</jats:italic>/<jats:italic>R</jats:italic> with different excitation photon energies. Employing the boundary conditions given by the Fresnel equations, we analyze the transient transmission/reflection spectra across the main excitonic resonances of 1L-MoS<jats:sub>2</jats:sub>. We show that pure interference effects induced by the different substrates explain the substantial differences (<jats:italic>i.e.</jats:italic>, intensity, peak energy and exciton linewidth) observed in the transient spectra of the same monolayer. We thus demonstrate that the substrate strongly affects the magnitude of the exciton energy shift and the change of the oscillator strength in the transient optical spectra. By highlighting the key role played by the substrate, our results set the stage for a unified interpretation of the transient response of optoelectronic devices based on a broad class of TMDs.</jats:p>
2022
Fulvio Paleari, Andrea Marini
Exciton-phonon interaction calls for a revision of the “exciton” concept Journal Article
In: Physical Review B, vol. 106, iss. 12, pp. 125403, 2022.
Abstract | Links | BibTeX | Tag: and Optics, Atomic and Molecular Physics, General Engineering, General Materials Science, General Physics and Astronomy
@article{,
title = {Exciton-phonon interaction calls for a revision of the “exciton” concept},
author = {Fulvio Paleari, Andrea Marini},
editor = {American Physical Society},
url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.125403
},
doi = {https://doi.org/10.1103/PhysRevB.106.125403},
year = {2022},
date = {2022-09-15},
urldate = {2022-09-15},
journal = {Physical Review B},
volume = {106},
issue = {12},
pages = {125403},
abstract = {The concept of optical exciton—a photoexcited bound electron-hole pair within a crystal—is routinely used to interpret and model a wealth of excited-state phenomena in semiconductors. Beside originating subband gap signatures in optical spectra, optical excitons have also been predicted to condensate, diffuse, recombine, and relax. However, all these phenomena are rooted on a theoretical definition of the excitonic state based on the following simple picture: “excitons” are actual particles that both appear as peaks in the linear absorption spectrum and also behave as well-defined quasiparticles. In this paper, we show, instead, that the electron–phonon interaction decomposes the initial optical (i.e., “reducible”) excitons into elemental (i.e., “irreducible”) excitons, the latter being a different kind of bound electron-hole pairs lacking the effect caused by the induced, classical, electric field. This is demonstrated within a real-time, many-body perturbation theory approach starting from the interacting electronic Hamiltonian including both electron-phonon and electron-hole interactions. We then apply the results to two realistic and paradigmatic systems, monolayer MoS2 (where the lowest-bound optical exciton is optically inactive) and monolayer MoSe2 (where it is optically active), using first-principles methods to compute the exciton-phonon coupling matrix elements. Among the consequences of optical-elemental decomposition, we point to a homogeneous broadening of absorption peaks occurring even for the lowest-bound optical exciton , and we demonstrate this by computing exciton-phonon transition rates. More generally, our findings suggest that the optical excitons gradually lose their initial structure and evolve as elemental excitons. These states can be regarded as the real intrinsic excitations of the interacting system, the ones that survive when the external perturbation and the induced electric fields have vanished.},
keywords = {and Optics, Atomic and Molecular Physics, General Engineering, General Materials Science, General Physics and Astronomy},
pubstate = {published},
tppubtype = {article}
}
The concept of optical exciton—a photoexcited bound electron-hole pair within a crystal—is routinely used to interpret and model a wealth of excited-state phenomena in semiconductors. Beside originating subband gap signatures in optical spectra, optical excitons have also been predicted to condensate, diffuse, recombine, and relax. However, all these phenomena are rooted on a theoretical definition of the excitonic state based on the following simple picture: “excitons” are actual particles that both appear as peaks in the linear absorption spectrum and also behave as well-defined quasiparticles. In this paper, we show, instead, that the electron–phonon interaction decomposes the initial optical (i.e., “reducible”) excitons into elemental (i.e., “irreducible”) excitons, the latter being a different kind of bound electron-hole pairs lacking the effect caused by the induced, classical, electric field. This is demonstrated within a real-time, many-body perturbation theory approach starting from the interacting electronic Hamiltonian including both electron-phonon and electron-hole interactions. We then apply the results to two realistic and paradigmatic systems, monolayer MoS2 (where the lowest-bound optical exciton is optically inactive) and monolayer MoSe2 (where it is optically active), using first-principles methods to compute the exciton-phonon coupling matrix elements. Among the consequences of optical-elemental decomposition, we point to a homogeneous broadening of absorption peaks occurring even for the lowest-bound optical exciton , and we demonstrate this by computing exciton-phonon transition rates. More generally, our findings suggest that the optical excitons gradually lose their initial structure and evolve as elemental excitons. These states can be regarded as the real intrinsic excitations of the interacting system, the ones that survive when the external perturbation and the induced electric fields have vanished.
A; Perfetto Marini, E; Stefanucci, G
Coherence and de-coherence in the Time-Resolved ARPES of realistic materials: An ab-initio perspective Journal Article
In: JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA, vol. 257, no 147189, 2022, ISSN: 03682048.
Abstract | Links | BibTeX | Tag:
@article{nokey,
title = {Coherence and de-coherence in the Time-Resolved ARPES of realistic materials: An ab-initio perspective},
author = {Marini, A; Perfetto, E and Stefanucci, G},
editor = {Elsevier},
url = {https://www.sciencedirect.com/science/article/abs/pii/S0368204822000299},
doi = {10.1016/j.elspec.2022.147189},
issn = {03682048},
year = {2022},
date = {2022-05-01},
urldate = {2022-05-01},
journal = {JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA},
volume = {257},
number = {147189},
abstract = {Coherence and de-coherence are the most fundamental steps that follow the initial photo-excitation occurring in typical pump-and-probe experiments. Indeed, the initial external laser pulse transfers coherence to the system in terms of creation of multiple electron-hole pairs excitation. The excitation concurs both to the creation of a finite carriers density and to the appearance of induced electromagnetic fields. The two effects, to a very first approximation, can be connected to the simple concepts of populations and oscillations. The dynamics of the system following the initial photo-excitation is, thus, entirely dictated by the interplay between coherence and de-coherence. This interplay and the de-coherence process itself, is due to the correlation effects stimulated by the photo-excitation. Single-particle, like the electron-phonon, and two-particles, like the electron-electron, scattering processes induce a complex dynamics of the electrons that, in turn, makes the description of the correlated and photo-excited system in terms of pure excitonic and/or carriers populations challenging.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Coherence and de-coherence are the most fundamental steps that follow the initial photo-excitation occurring in typical pump-and-probe experiments. Indeed, the initial external laser pulse transfers coherence to the system in terms of creation of multiple electron-hole pairs excitation. The excitation concurs both to the creation of a finite carriers density and to the appearance of induced electromagnetic fields. The two effects, to a very first approximation, can be connected to the simple concepts of populations and oscillations. The dynamics of the system following the initial photo-excitation is, thus, entirely dictated by the interplay between coherence and de-coherence. This interplay and the de-coherence process itself, is due to the correlation effects stimulated by the photo-excitation. Single-particle, like the electron-phonon, and two-particles, like the electron-electron, scattering processes induce a complex dynamics of the electrons that, in turn, makes the description of the correlated and photo-excited system in terms of pure excitonic and/or carriers populations challenging.
CEP (Villegas Villegas, Cesar E. P. ) ; Leite
Efficient hot-carrier dynamics in near-infrared photocatalytic metals Journal Article
In: Physical Review B, vol. 105, iss. 16, no 165109, 2022, ISSN: 2469-9950; eISSN 2469-9969.
Abstract | Links | BibTeX | Tag: Applied, Atomic and Molecular Physics, Condensed matter, General Materials Science, General Physics and Astronomy, Multidisciplinary, Physics
@article{nokey,
title = {Efficient hot-carrier dynamics in near-infrared photocatalytic metals},
author = {Villegas, CEP (Villegas, Cesar E. P.) ; Leite, MS (Leite, Marina S.) ; Marini, A (Marini, Andrea) ; Rocha, AR (Rocha, Alexandre R.)},
editor = {AMER PHYSICAL SOC},
url = {https://www.webofscience.com/wos/woscc/full-record/WOS:000807392800005},
doi = {10.1103/PhysRevB.105.165109},
issn = {2469-9950; eISSN 2469-9969},
year = {2022},
date = {2022-04-07},
journal = {Physical Review B},
volume = {105},
number = {165109},
issue = {16},
abstract = {Photoexcited metals can produce highly energetic hot carriers whose controlled generation and extraction is a promising avenue for technological applications. While hot-carrier dynamics in Au-group metals have been widely investigated, a microscopic description of the dynamics of photoexcited carriers in the mid-infrared and near-infrared Pt-group metals range is still scarce. Since these materials are widely used in catalysis and, more recently, in plasmonic catalysis, their microscopic carrier dynamics characterization is crucial. We employ ab initio many-body perturbation theory to investigate the hot-carrier generation, relaxation times, and mean free path in bulk Pd and Pt. We show that the direct optical transitions of photoexcited carriers in these metals are mainly generated in the near-infrared range. We also find that the electron-phonon mass enhancement parameter for Pt is 16% higher than Pd, a result that helps explain several experimental results showing diverse trends. Moreover, we predict that Pd (Pt) hot electrons possess total relaxation times of up to 35 fs (24 fs), taking place at approximately 0.5 eV (1.0 eV) above the Fermi energy. Finally, an efficient hot electron generation and extraction can be achieved in nanofilms of Pd (110) and Pd (100) when subject to excitation energies ranging from 0.4 to 1.6 eV.},
keywords = {Applied, Atomic and Molecular Physics, Condensed matter, General Materials Science, General Physics and Astronomy, Multidisciplinary, Physics},
pubstate = {published},
tppubtype = {article}
}
Photoexcited metals can produce highly energetic hot carriers whose controlled generation and extraction is a promising avenue for technological applications. While hot-carrier dynamics in Au-group metals have been widely investigated, a microscopic description of the dynamics of photoexcited carriers in the mid-infrared and near-infrared Pt-group metals range is still scarce. Since these materials are widely used in catalysis and, more recently, in plasmonic catalysis, their microscopic carrier dynamics characterization is crucial. We employ ab initio many-body perturbation theory to investigate the hot-carrier generation, relaxation times, and mean free path in bulk Pd and Pt. We show that the direct optical transitions of photoexcited carriers in these metals are mainly generated in the near-infrared range. We also find that the electron-phonon mass enhancement parameter for Pt is 16% higher than Pd, a result that helps explain several experimental results showing diverse trends. Moreover, we predict that Pd (Pt) hot electrons possess total relaxation times of up to 35 fs (24 fs), taking place at approximately 0.5 eV (1.0 eV) above the Fermi energy. Finally, an efficient hot electron generation and extraction can be achieved in nanofilms of Pd (110) and Pd (100) when subject to excitation energies ranging from 0.4 to 1.6 eV.
2021
Davide Sangalli Federico Pressacco, Vojtěch Uhlíř
Subpicosecond metamagnetic phase transition in FeRh driven by non-equilibrium electron dynamics Journal Article
In: Nature Communications, vol. 12, iss. 1, pp. 5088, 2021, ISSN: 2041-1723 (online).
Abstract | Links | BibTeX | Tag:
@article{nokey,
title = {Subpicosecond metamagnetic phase transition in FeRh driven by non-equilibrium electron dynamics},
author = {Federico Pressacco, Davide Sangalli, Vojtěch Uhlíř, Dmytro Kutnyakhov, Jon Ander Arregi, Steinn Ymir Agustsson, Günter Brenner, Harald Redlin, Michael Heber, Dmitry Vasilyev, Jure Demsar, Gerd Schönhense, Matteo Gatti, Andrea Marini, Wilfried Wurth, Fausto Sirotti},
editor = {Nature Publishing Group UK},
url = {https://rdcu.be/d4hLP},
doi = {https://doi.org/10.1038/s41467-021-25347-3},
issn = {2041-1723 (online)},
year = {2021},
date = {2021-08-24},
journal = {Nature Communications},
volume = {12},
issue = {1},
pages = {5088},
abstract = {Femtosecond light-induced phase transitions between different macroscopic orders provide the possibility to tune the functional properties of condensed matter on ultrafast timescales. In first-order phase transitions, transient non-equilibrium phases and inherent phase coexistence often preclude non-ambiguous detection of transition precursors and their temporal onset. Here, we present a study combining time-resolved photoelectron spectroscopy and ab-initio electron dynamics calculations elucidating the transient subpicosecond processes governing the photoinduced generation of ferromagnetic order in antiferromagnetic FeRh. The transient photoemission spectra are accounted for by assuming that not only the occupation of electronic states is modified during the photoexcitation process. Instead, the photo-generated non-thermal distribution of electrons modifies the electronic band structure. The ferromagnetic phase of FeRh, characterized by a minority band near the Fermi energy, is established 350 ± 30 fs after the laser excitation. Ab-initio calculations indicate that the phase transition is initiated by a photoinduced Rh-to-Fe charge transfer.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Femtosecond light-induced phase transitions between different macroscopic orders provide the possibility to tune the functional properties of condensed matter on ultrafast timescales. In first-order phase transitions, transient non-equilibrium phases and inherent phase coexistence often preclude non-ambiguous detection of transition precursors and their temporal onset. Here, we present a study combining time-resolved photoelectron spectroscopy and ab-initio electron dynamics calculations elucidating the transient subpicosecond processes governing the photoinduced generation of ferromagnetic order in antiferromagnetic FeRh. The transient photoemission spectra are accounted for by assuming that not only the occupation of electronic states is modified during the photoexcitation process. Instead, the photo-generated non-thermal distribution of electrons modifies the electronic band structure. The ferromagnetic phase of FeRh, characterized by a minority band near the Fermi energy, is established 350 ± 30 fs after the laser excitation. Ab-initio calculations indicate that the phase transition is initiated by a photoinduced Rh-to-Fe charge transfer.
A Molina-Sánchez M Marsili, M Palummo
Spinorial formulation of the -BSE equations and spin properties of excitons in two-dimensional transition metal dichalcogenides Journal Article
In: Physical Review B, vol. 103, iss. 15, pp. 155152, 2021, ISSN: 2469-9969 (online), 2469-9950 (print).
Abstract | Links | BibTeX | Tag: and Optics, Atomic and Molecular Physics, General Engineering, General Materials Science, General Physics and Astronomy
@article{nokey,
title = {Spinorial formulation of the -BSE equations and spin properties of excitons in two-dimensional transition metal dichalcogenides},
author = {M Marsili, A Molina-Sánchez, M Palummo, D Sangalli, A Marini},
editor = {American Physical Society},
url = {https://journals.aps.org/prb/pdf/10.1103/PhysRevB.103.155152},
doi = { https://doi.org/10.1103/PhysRevB.103.155152},
issn = {2469-9969 (online), 2469-9950 (print)},
year = {2021},
date = {2021-04-15},
journal = {Physical Review B},
volume = {103},
issue = {15},
pages = {155152},
abstract = {In many paradigmatic materials, such as transition metal dichalcogenides, the role played by the spin degrees of freedom is as important as the one played by the electron-electron interaction. Thus an accurate treatment of the two effects and of their interaction is necessary for an accurate and predictive study of the optical and electronic properties of these materials. Despite the fact that the GW-BSE approach correctly accounts for electronic correlations, the spin-orbit coupling effect is often neglected or treated perturbatively. Recently, spinorial formulations of GW-BSE have become available in different flavors in material-science codes. However, an accurate validation and comparison of different approaches is still missing. In this work, we go through the derivation of the noncollinear GW-BSE approach. The scheme is applied to transition metal dichalcogenides comparing the perturbative and full spinorial approaches. Our calculations reveal that dark-bright exciton splittings are generally improved when the spin-orbit coupling is included nonperturbatively. The exchange-driven intravalley mixing between the A and B excitons is found to play a role for Mo-based systems, being especially strong in the case of MoSe2. We finally compute the excitonic spin and use it to sharply analyze the spinorial properties of transition metal dichalcogenide excitonic states.},
keywords = {and Optics, Atomic and Molecular Physics, General Engineering, General Materials Science, General Physics and Astronomy},
pubstate = {published},
tppubtype = {article}
}
In many paradigmatic materials, such as transition metal dichalcogenides, the role played by the spin degrees of freedom is as important as the one played by the electron-electron interaction. Thus an accurate treatment of the two effects and of their interaction is necessary for an accurate and predictive study of the optical and electronic properties of these materials. Despite the fact that the GW-BSE approach correctly accounts for electronic correlations, the spin-orbit coupling effect is often neglected or treated perturbatively. Recently, spinorial formulations of GW-BSE have become available in different flavors in material-science codes. However, an accurate validation and comparison of different approaches is still missing. In this work, we go through the derivation of the noncollinear GW-BSE approach. The scheme is applied to transition metal dichalcogenides comparing the perturbative and full spinorial approaches. Our calculations reveal that dark-bright exciton splittings are generally improved when the spin-orbit coupling is included nonperturbatively. The exchange-driven intravalley mixing between the A and B excitons is found to play a role for Mo-based systems, being especially strong in the case of MoSe2. We finally compute the excitonic spin and use it to sharply analyze the spinorial properties of transition metal dichalcogenide excitonic states.
Smejkal, Valerie; Libisch, Florian; Molina-Sanchez, Alejandro; Trovatello, Chiara; Wirtz, Ludger; Marini, Andrea
Time-Dependent Screening Explains the Ultrafast Excitonic Signal Rise in 2D Semiconductors Journal Article
In: ACS Nano, vol. 15, no 1, pp. 1179–1185, 2021, ISSN: 1936-086X.
Links | BibTeX | Tag: General Engineering, General Materials Science, General Physics and Astronomy, Nanoscience, Nanotechnology
@article{Smejkal2020,
title = {Time-Dependent Screening Explains the Ultrafast Excitonic Signal Rise in 2D Semiconductors},
author = {Valerie Smejkal and Florian Libisch and Alejandro Molina-Sanchez and Chiara Trovatello and Ludger Wirtz and Andrea Marini},
doi = {10.1021/acsnano.0c08173},
issn = {1936-086X},
year = {2021},
date = {2021-01-26},
urldate = {2021-01-26},
journal = {ACS Nano},
volume = {15},
number = {1},
pages = {1179–1185},
publisher = {American Chemical Society (ACS)},
keywords = {General Engineering, General Materials Science, General Physics and Astronomy, Nanoscience, Nanotechnology},
pubstate = {published},
tppubtype = {article}
}
2020
Mauro Del Ben c Tonatiuh Rangel, Daniele Varsano
Reproducibility in G0W0 calculations for solids Journal Article
In: Computer Physics Communications, vol. 255, pp. 107242, 2020, ISSN: 0010-4655 Online ISSN: 1879-2944.
Abstract | Links | BibTeX | Tag:
@article{nokey,
title = {Reproducibility in G0W0 calculations for solids},
author = {Tonatiuh Rangel, Mauro Del Ben c, Daniele Varsano, Gabriel Antonius,
Fabien Bruneval, Felipe H. da Jornada, Michiel J. van Setten, Okan K. Orhan,
David D. O’Regan, Andrew Canning, Andrea Ferretti, Andrea Marini, Gian-Marco Rignanese, Jack Deslippe, Steven G. Louie, Jeffrey B. Neaton },
editor = {North-Holland},
url = {https://pdf.sciencedirectassets.com/271575/1-s2.0-S0010465520X00087/1-s2.0-S0010465520300734/main.pdf?X-Amz-Security-Token=IQoJb3JpZ2luX2VjEMT%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEaCXVzLWVhc3QtMSJHMEUCIQCF62nE7DuRrBWT%2FbMLddOBRtwfDGMxZhOAo3QXvLlqgAIgPuG6RLu73dbkiuWBGB51Vto7BQ4w60RZ%2Fe%2Bf22O68EAqvAUIjf%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FARAFGgwwNTkwMDM1NDY4NjUiDDUSjbHss2oVx8Gd0yqQBZDggwV1lFmO8gLG3HzHJeXqImbX945LdX1eQ1A8OC4RHA2f2WpIh%2Fp%2B3UQKAR22bOUsHsnG1NH%2FZXTLrJUQfVaHVuDS9DewckxpJZrRLHWZBizNeVx2zfoRb30V1uMxaPkldogzOXmND0iXVj3f%2FLOk4kYmHwDSy4QcgBx3z5lwNfDA2nm86zS1CNRHylHO2extm5I9Imbqeylr7kJKvdyPy2iZYsdjdGv59Vyc4bMtVHfXprtfJZGaOZx7%2BzLWsAlrSnfoDZktRASJ4xZNOoD6cIlQ%2FG7JSwPhgPVmwXLEBDEnGP5G1I4XX0kRZECBIVBZujmtLdm2mkLiG3oAfK8uUU60PEB%2BupCGGEt33bfFlLJNFR4TyfzUbebYTUOKbhbiRQTyNOKoq0PnWltNgSN8fJMmxpAsxqObgIh%2FUYH4IoMd%2B2faDDzOfXXAW69yUgReQW9EACBZpM7fqz0ijroE6csOV8Ol9sRNwp122WVATQICX8LCR9SOwz10u%2FlJezTPD2pCzGEWRwbNvD9PDs4iIXuBYChq5oBwXnNU3UjZd8hIDCobu06s06Qf6iZLpPo1YILHFMW6jVK89KVWmmF%2FSbaNs22R%2B%2Ba3jXZ2L%2FOeRsvle46cWx%2BmVM9STdZ8s5nIt0R4X8239ckXZ2w81Sy%2BtwSFBJgCIY4YfxHhA5f3lDj4god0JfFR5zj6iobUhUvTvr%2FUwZ4QFNdWwdYdtbJE88i19hbSqxyFWrKh%2FQbuldSzy1aiJSO2wz4xhycQmjf7z3cMrYGdoaMM7As4XZDf2zVKqTsE8no0m66DPen437kZP0pDm2VfdEttrgMpWtKVGmLIQ5I1dsY4O4p9WCWbwLFm8AXF499SAuh0WVoyMOG2lbsGOrEBtOnHz%2BQ1LXV4k3pAdTXOBxEedUuaAot%2B1%2Bqg1e7bo%2F9eKjK%2BxjFZdYxslyUELY%2B3%2F2ib9X3O1bvY5J%2FQHrrQ56G1CjQW%2FyLj%2BoOd0n5z4DrG%2By3DATiAmoo%2FQOn3X3ui0etP0YvD%2F2AnxA0EwzCRS4cZNJWcISTkrnc%2BM2mQv7xKmyUxD8Y1VytN8rMKpPys8jZmDb4j2hK2bw6OmUFY9c3PlcuQcKnaY13vaIDhp1Rk&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20241220T125646Z&X-Amz-SignedHeaders=host&X-Amz-Expires=300&X-Amz-Credential=ASIAQ3PHCVTY2G6IKVKY%2F20241220%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=692d0668e88e372f4eaa2866333e9dc69ed37841dec1d2530bf21ff77c1f60cd&hash=782468c9e6ad2e088f0365acb7557bb8c973520d6d4e552cc03d10bb2dc4800d&host=68042c943591013ac2b2430a89b270f6af2c76d8dfd086a07176afe7c76c2c61&pii=S0010465520300734&tid=spdf-44500ee1-caf8-49f9-969a-da76435bddf2&sid=974eba3a12cac047a93b839143f879094241gxrqb&type=client&tsoh=d3d3LnNjaWVuY2VkaXJlY3QuY29t&ua=0f145e0252040c07565b&rr=8f4fcb58aa1ef940&cc=it},
doi = {https://doi.org/10.1016/j.cpc.2020.107242},
issn = {0010-4655 Online ISSN: 1879-2944},
year = {2020},
date = {2020-10-01},
urldate = {2020-10-01},
journal = {Computer Physics Communications},
volume = {255},
pages = {107242},
abstract = {Ab initio many-body perturbation theory within the GW approximation is a Green’s function formalism
widely used in the calculation of quasiparticle excitation energies of solids. In what has become an
increasingly standard approach, Kohn–Sham eigenenergies, generated from a DFT calculation with a
strategically-chosen exchange–correlation functional ‘‘starting point’’, are used to construct G and W,
and then perturbatively corrected by the resultant GW self-energy. In practice, there are several ways
to construct the GW self-energy, and these can lead to variations in predicted quasiparticle energies.
For example, for ZnO and TiO2, the GW fundamental gaps reported in the literature can vary by more
than 1 eV depending on the GW code used. In this work, we calculate and analyze GW quasiparticle
(QP) energies of these and other systems with three different GW codes: BerkeleyGW, Abinit and
Yambo. Through a systematic analysis of the GW implementation of these three codes, we identify the
primary origin of major discrepancies between codes reported in prior literature to be the different
implementations the Coulomb divergence in the Fock exchange term and the frequency integration
scheme of the GW self-energy. We then eliminate these discrepancies by using common numerical
methods and algorithms, demonstrating that the same quasiparticle energies for a given material can
be obtained with different codes, within numerical differences ascribable to the technical details of
the underling implementations. This work will be important for users and developers in assessing the
precision of future GW applications and methods.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Ab initio many-body perturbation theory within the GW approximation is a Green’s function formalism
widely used in the calculation of quasiparticle excitation energies of solids. In what has become an
increasingly standard approach, Kohn–Sham eigenenergies, generated from a DFT calculation with a
strategically-chosen exchange–correlation functional ‘‘starting point’’, are used to construct G and W,
and then perturbatively corrected by the resultant GW self-energy. In practice, there are several ways
to construct the GW self-energy, and these can lead to variations in predicted quasiparticle energies.
For example, for ZnO and TiO2, the GW fundamental gaps reported in the literature can vary by more
than 1 eV depending on the GW code used. In this work, we calculate and analyze GW quasiparticle
(QP) energies of these and other systems with three different GW codes: BerkeleyGW, Abinit and
Yambo. Through a systematic analysis of the GW implementation of these three codes, we identify the
primary origin of major discrepancies between codes reported in prior literature to be the different
implementations the Coulomb divergence in the Fock exchange term and the frequency integration
scheme of the GW self-energy. We then eliminate these discrepancies by using common numerical
methods and algorithms, demonstrating that the same quasiparticle energies for a given material can
be obtained with different codes, within numerical differences ascribable to the technical details of
the underling implementations. This work will be important for users and developers in assessing the
precision of future GW applications and methods.
widely used in the calculation of quasiparticle excitation energies of solids. In what has become an
increasingly standard approach, Kohn–Sham eigenenergies, generated from a DFT calculation with a
strategically-chosen exchange–correlation functional ‘‘starting point’’, are used to construct G and W,
and then perturbatively corrected by the resultant GW self-energy. In practice, there are several ways
to construct the GW self-energy, and these can lead to variations in predicted quasiparticle energies.
For example, for ZnO and TiO2, the GW fundamental gaps reported in the literature can vary by more
than 1 eV depending on the GW code used. In this work, we calculate and analyze GW quasiparticle
(QP) energies of these and other systems with three different GW codes: BerkeleyGW, Abinit and
Yambo. Through a systematic analysis of the GW implementation of these three codes, we identify the
primary origin of major discrepancies between codes reported in prior literature to be the different
implementations the Coulomb divergence in the Fock exchange term and the frequency integration
scheme of the GW self-energy. We then eliminate these discrepancies by using common numerical
methods and algorithms, demonstrating that the same quasiparticle energies for a given material can
be obtained with different codes, within numerical differences ascribable to the technical details of
the underling implementations. This work will be important for users and developers in assessing the
precision of future GW applications and methods.
R Patrick Xian Maciej Dendzik, Enrico Perfetto
Observation of an Excitonic Mott Transition through Ultrafast Core-cum-Conduction Photoemission Spectroscopy Journal Article
In: Physical review letters, vol. 125, iss. 9, pp. 096401, 2020, ISSN: 1079-7114 (online), 0031-9007 (print).
Abstract | Links | BibTeX | Tag: and Optics, Atomic and Molecular Physics, General Engineering, General Materials Science, General Physics and Astronomy
@article{nokey,
title = {Observation of an Excitonic Mott Transition through Ultrafast Core-cum-Conduction Photoemission Spectroscopy},
author = {Maciej Dendzik, R Patrick Xian, Enrico Perfetto, Davide Sangalli, Dmytro Kutnyakhov, Shuo Dong, Samuel Beaulieu, Tommaso Pincelli, Federico Pressacco, Davide Curcio, Steinn Ymir Agustsson, Michael Heber, Jasper Hauer, Wilfried Wurth, Günter Brenner, Yves Acremann, Philip Hofmann, Martin Wolf, Andrea Marini, Gianluca Stefanucci, Laurenz Rettig, Ralph Ernstorfer},
editor = {American Physical Society},
url = {https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.125.096401},
doi = {https://doi.org/10.1103/PhysRevLett.125.096401},
issn = {1079-7114 (online), 0031-9007 (print)},
year = {2020},
date = {2020-08-28},
urldate = {2020-08-28},
journal = {Physical review letters},
volume = {125},
issue = {9},
pages = {096401},
abstract = {Time-resolved soft-x-ray photoemission spectroscopy is used to simultaneously measure the ultrafast dynamics of core-level spectral functions and excited states upon excitation of excitons in WSe2. We present a many-body approximation for the Green’s function, which excellently describes the transient core-hole spectral function. The relative dynamics of excited-state signal and core levels clearly show a delayed core-hole renormalization due to screening by excited quasifree carriers resulting from an excitonic Mott transition. These findings establish time-resolved core-level photoelectron spectroscopy as a sensitive probe of subtle electronic many-body interactions and ultrafast electronic phase transitions.},
keywords = {and Optics, Atomic and Molecular Physics, General Engineering, General Materials Science, General Physics and Astronomy},
pubstate = {published},
tppubtype = {article}
}
Time-resolved soft-x-ray photoemission spectroscopy is used to simultaneously measure the ultrafast dynamics of core-level spectral functions and excited states upon excitation of excitons in WSe2. We present a many-body approximation for the Green’s function, which excellently describes the transient core-hole spectral function. The relative dynamics of excited-state signal and core levels clearly show a delayed core-hole renormalization due to screening by excited quasifree carriers resulting from an excitonic Mott transition. These findings establish time-resolved core-level photoelectron spectroscopy as a sensitive probe of subtle electronic many-body interactions and ultrafast electronic phase transitions.
E; Marini Perfetto, A; Stefanucci
Self-consistent screening enhances the stability of the nonequilibrium excitonic insulator phase Journal Article
In: Physical Review B, vol. 102, iss. 8, no 085203, 2020, ISSN: 2469-9950; eISSN 2469-9969.
Abstract | Links | BibTeX | Tag: Condensed matter, General Materials Science, Multidisciplinary, Nanoscience
@article{nokey,
title = {Self-consistent screening enhances the stability of the nonequilibrium excitonic insulator phase},
author = {Perfetto, E; Marini, A; Stefanucci, G},
editor = {AMER PHYSICAL SOC},
doi = {10.1103/PhysRevB.102.085203},
issn = {2469-9950; eISSN 2469-9969},
year = {2020},
date = {2020-08-24},
urldate = {2020-08-24},
journal = {Physical Review B},
volume = {102},
number = {085203},
issue = {8},
abstract = {The nonequilibrium excitonic insulator (NEQ-EI) is an excited state of matter characterized by a finite density of coherent excitons and a time-dependent macroscopic polarization. The stability of this exciton superfluid as the density grows is jeopardized by the increased screening efficiency of the looser excitons. In this work we put forward a Hartree plus screened exchange scheme to predict the critical density at which the transition toward a free electron-hole plasma occurs. The dielectric function is calculated self-consistently using the NEQ-EI polarization and found to vanish in the long-wavelength limit. This property makes the exciton superfluid stable up to relatively high densities. Numerical results for the MoS2 monolayers indicate that the NEQ-EI phase survives up to densities of the order of 10(12) cm(-)(2).},
keywords = {Condensed matter, General Materials Science, Multidisciplinary, Nanoscience},
pubstate = {published},
tppubtype = {article}
}
The nonequilibrium excitonic insulator (NEQ-EI) is an excited state of matter characterized by a finite density of coherent excitons and a time-dependent macroscopic polarization. The stability of this exciton superfluid as the density grows is jeopardized by the increased screening efficiency of the looser excitons. In this work we put forward a Hartree plus screened exchange scheme to predict the critical density at which the transition toward a free electron-hole plasma occurs. The dielectric function is calculated self-consistently using the NEQ-EI polarization and found to vanish in the long-wavelength limit. This property makes the exciton superfluid stable up to relatively high densities. Numerical results for the MoS2 monolayers indicate that the NEQ-EI phase survives up to densities of the order of 10(12) cm(-)(2).
Trovatello, Chiara; Miranda, Henrique P. C.; Molina-Sánchez, Alejandro; Borrego-Varillas, Rocío; Manzoni, Cristian; Moretti, Luca; Ganzer, Lucia; Maiuri, Margherita; Wang, Junjia; Dumcenco, Dumitru; Kis, Andras; Wirtz, Ludger; Marini, Andrea; Soavi, Giancarlo; Ferrari, Andrea C.; Cerullo, Giulio; Sangalli, Davide; Conte, Stefano Dal
Strongly Coupled Coherent Phonons in Single-Layer MoS_2 Journal Article
In: ACS Nano, vol. 14, no 5, pp. 5700–5710, 2020, ISSN: 1936-086X.
Links | BibTeX | Tag: General Engineering, General Materials Science, General Physics and Astronomy
@article{Trovatello2020,
title = {Strongly Coupled Coherent Phonons in Single-Layer MoS_2},
author = {Chiara Trovatello and Henrique P. C. Miranda and Alejandro Molina-Sánchez and Rocío Borrego-Varillas and Cristian Manzoni and Luca Moretti and Lucia Ganzer and Margherita Maiuri and Junjia Wang and Dumitru Dumcenco and Andras Kis and Ludger Wirtz and Andrea Marini and Giancarlo Soavi and Andrea C. Ferrari and Giulio Cerullo and Davide Sangalli and Stefano Dal Conte},
doi = {10.1021/acsnano.0c00309},
issn = {1936-086X},
year = {2020},
date = {2020-05-26},
journal = {ACS Nano},
volume = {14},
number = {5},
pages = {5700–5710},
publisher = {American Chemical Society (ACS)},
keywords = {General Engineering, General Materials Science, General Physics and Astronomy},
pubstate = {published},
tppubtype = {article}
}
E; Trabattoni Perfetto, A; Stefanucci
Ultrafast Quantum Interference in the Charge Migration of Tryptophan Journal Article
In: JOURNAL OF PHYSICAL CHEMISTRY LETTERS, vol. 11, iss. 3, pp. 891-899, 2020, ISSN: 1948-7185.
Abstract | Links | BibTeX | Tag: Atomic and Molecular Physics, Chemistry
@article{nokey,
title = {Ultrafast Quantum Interference in the Charge Migration of Tryptophan},
author = {Perfetto, E; Trabattoni, A; Stefanucci, G},
editor = {AMER CHEMICAL SOC},
doi = {10.1021/acs.jpclett.9b03517},
issn = {1948-7185},
year = {2020},
date = {2020-02-06},
urldate = {2020-02-06},
journal = {JOURNAL OF PHYSICAL CHEMISTRY LETTERS},
volume = {11},
issue = {3},
pages = {891-899},
abstract = {Extreme-ultraviolet-induced charge migration in biorelevant molecules is a fundamental step in the complex path leading to photodamage. In this work we propose a simple interpretation of the charge migration recently observed in an attosecond pump-probe experiment on the amino acid tryptophan. We find that the decay of the prominent low-frequency spectral structure with increasing pump-probe delay is due to a quantum beating between two geometrically distinct, almost degenerate charge oscillations. Quantum beating is ubiquitous in these systems, and at least on the few-to-tens of femtosecond time scales, it may dominate over decoherence the line intensities of time-resolved spectra. We also address the experimentally observed phase shift in the charge oscillations of two different amino acids, tryptophan and phenylalanine. Our results indicate that a beyond mean-field treatment of the electron dynamics is necessary to reproduce the correct behavior.},
keywords = {Atomic and Molecular Physics, Chemistry},
pubstate = {published},
tppubtype = {article}
}
Extreme-ultraviolet-induced charge migration in biorelevant molecules is a fundamental step in the complex path leading to photodamage. In this work we propose a simple interpretation of the charge migration recently observed in an attosecond pump-probe experiment on the amino acid tryptophan. We find that the decay of the prominent low-frequency spectral structure with increasing pump-probe delay is due to a quantum beating between two geometrically distinct, almost degenerate charge oscillations. Quantum beating is ubiquitous in these systems, and at least on the few-to-tens of femtosecond time scales, it may dominate over decoherence the line intensities of time-resolved spectra. We also address the experimentally observed phase shift in the charge oscillations of two different amino acids, tryptophan and phenylalanine. Our results indicate that a beyond mean-field treatment of the electron dynamics is necessary to reproduce the correct behavior.
D (Aquaro Aquaro, Donato) ; Ibba
Deposition of ITER Vacuum Vessel Dust Inside the Pressure Suppression System During a Loss of Coolant Accident: Experimental and Numerical Analyses Proceedings Article
In: 2020), 29TH INTERNATIONAL CONFERENCE NUCLEAR ENERGY FOR NEW EUROPE (NENE (Ed.): Snoj, L (Snoj, L) ; Cufar, A (Cufar, A), 2020, ISBN: 978-961-6207-49-2.
Abstract | Links | BibTeX | Tag: Environmental studies, Nuclear Science & Technology
@inproceedings{nokey,
title = {Deposition of ITER Vacuum Vessel Dust Inside the Pressure Suppression System During a Loss of Coolant Accident: Experimental and Numerical Analyses},
author = {Aquaro, D (Aquaro, Donato) ; Ibba, M (Ibba, Miriam) ; Lazzeri, R (Lazzeri, Roberta) ; Pesetti, A (Pesetti, Alessio) ; Marini, A (Marini, Andrea) ; Parozzi, F (Parozzi, Flavio) ; Sarkar, B (Sarkar, Bismanath) ; Olcese, M (Olcese, Marco)},
editor = {29TH INTERNATIONAL CONFERENCE NUCLEAR ENERGY FOR NEW EUROPE (NENE 2020)},
url = {https://www.webofscience.com/wos/woscc/summary/2d26d387-fb01-44ff-b712-094cff54d2d7-014074b2a3/relevance/1},
isbn = {978-961-6207-49-2},
year = {2020},
date = {2020-01-01},
urldate = {2020-01-01},
publisher = {Snoj, L (Snoj, L) ; Cufar, A (Cufar, A)},
abstract = {This paper deals with an experimental and numerical analysis of the deposition of a simulant of ITER dust inside a reduced scale Vacuum Vessel Pressure Suppression System (VVPSS) of ITER. This research, funded by the ITER Organization, aims to analyse the dust deposition inside the VVPSS, the dust removal by means of robotised apparatuses and their decontamination efficiency. The experimental rig, built at the Department of Civil and Industrial Engineering (DICI) of the University of Pisa (Italy), is described and the results of the preliminary tests are illustrated. Furthermore, a numerical model of the experimental rig has been implemented in the code ECART to determine the relevance of different parameters on the deposition, resuspension and removal of dust. The numerical simulations allowed to define more precisely the test matrix and to analyse the experimental results.},
keywords = {Environmental studies, Nuclear Science & Technology},
pubstate = {published},
tppubtype = {inproceedings}
}
This paper deals with an experimental and numerical analysis of the deposition of a simulant of ITER dust inside a reduced scale Vacuum Vessel Pressure Suppression System (VVPSS) of ITER. This research, funded by the ITER Organization, aims to analyse the dust deposition inside the VVPSS, the dust removal by means of robotised apparatuses and their decontamination efficiency. The experimental rig, built at the Department of Civil and Industrial Engineering (DICI) of the University of Pisa (Italy), is described and the results of the preliminary tests are illustrated. Furthermore, a numerical model of the experimental rig has been implemented in the code ECART to determine the relevance of different parameters on the deposition, resuspension and removal of dust. The numerical simulations allowed to define more precisely the test matrix and to analyse the experimental results.
2019
E (Perfetto Perfetto, E. ) ; Sangalli
Pump-driven normal-to-excitonic insulator transition: Josephson oscillations and signatures of BEC-BCS crossover in time-resolved ARPES Journal Article
In: Physical review materials, vol. 3, iss. 12, no 124601, 2019, ISSN: 2475-9953.
Abstract | Links | BibTeX | Tag: General Materials Science, Multidisciplinary
@article{nokey,
title = {Pump-driven normal-to-excitonic insulator transition: Josephson oscillations and signatures of BEC-BCS crossover in time-resolved ARPES},
author = {Perfetto, E (Perfetto, E.) ; Sangalli, D (Sangalli, D.) ; Marini, A (Marini, A.) ; Stefanucci, G (Stefanucci, G.)},
editor = {AMER PHYSICAL SOC},
doi = {10.1103/PhysRevMaterials.3.124601},
issn = {2475-9953},
year = {2019},
date = {2019-12-16},
urldate = {2019-12-16},
journal = {Physical review materials},
volume = {3},
number = {124601},
issue = {12},
abstract = {We consider a ground-state band insulator turning into a nonequilibrium excitonic insulator (NEQ-EI) upon visiting properly selected and physically relevant highly excited states. The NEQ-EI phase, characterized by self-sustained oscillations of the complex order parameter, neatly follows from a nonequilibrium Green's function treatment on the Konstantinov-Perel' contour. We present the first ab initio band structure of LiF, a ground-state bulk insulator, in different NEQ-EI states. We also show that NEQ-EI states can be generated by currently available pump pulses. Peculiar fingerprints of the NEQ-EI phase in time-resolved angle-resolved photoemission spectroscopy spectra are highlighted: (i) during the pump-driving, the system goes through a BEC-BCS crossover and (ii) concomitantly the excitonic spectral structure undergoes a convex-to-concave shape transition; (iii) attosecond pulses shone after the pump-driving at different times t(delay) produce a photocurrent that oscillates in t(delay) with a pump-tunable frequency-we relate this phenomenon to the ac response of an exotic Josephson junction.},
keywords = {General Materials Science, Multidisciplinary},
pubstate = {published},
tppubtype = {article}
}
We consider a ground-state band insulator turning into a nonequilibrium excitonic insulator (NEQ-EI) upon visiting properly selected and physically relevant highly excited states. The NEQ-EI phase, characterized by self-sustained oscillations of the complex order parameter, neatly follows from a nonequilibrium Green's function treatment on the Konstantinov-Perel' contour. We present the first ab initio band structure of LiF, a ground-state bulk insulator, in different NEQ-EI states. We also show that NEQ-EI states can be generated by currently available pump pulses. Peculiar fingerprints of the NEQ-EI phase in time-resolved angle-resolved photoemission spectroscopy spectra are highlighted: (i) during the pump-driving, the system goes through a BEC-BCS crossover and (ii) concomitantly the excitonic spectral structure undergoes a convex-to-concave shape transition; (iii) attosecond pulses shone after the pump-driving at different times t(delay) produce a photocurrent that oscillates in t(delay) with a pump-tunable frequency-we relate this phenomenon to the ac response of an exotic Josephson junction.
C (Trovatello Trovatello, Chiara) ; Miranda
Strong Exciton-Coherent Phonon Coupling In Single-Layer MoS2 Proceedings Article
In: LASERS, 2019 CONFERENCE ON; (CLEO), ELECTRO-OPTICS (Ed.): Conference on Lasers and Electro-Optics, 2019, ISBN: 978-1-943580-57-6; ISSN 2160-9020.
Abstract | Links | BibTeX | Tag: Applied, Electric & Electronic, General Engineering, Optics, Physics
@inproceedings{nokey,
title = {Strong Exciton-Coherent Phonon Coupling In Single-Layer MoS2},
author = {Trovatello, C (Trovatello, Chiara) ; Miranda, HPC (Miranda, Henrique P. C.) ; Molina-Sánchez, A (Molina-Sanchez, Alejandro) ; Varillas, RB (Varillas, Rocio Borrego) ; Moretti, L (Moretti, Luca) ; Ganzer, L (Ganzer, Lucia) ; Maiuri, M (Maiuri, Margherita) ; Soavi, G (Soavi, Giancarlo) ; Ferrari, AC (Ferrari, Andrea C.) ; Marini, A (Marini, Andrea) ; Wirtz, L (Wirtz, Ludger) ; Cerullo, G (Cerullo, Giulio) ; Sangalli, D (Sangalli, Davide) ; Dal Conte, S (Dal Conte, Stefano)},
editor = {2019 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO)},
url = {https://www.webofscience.com/wos/woscc/summary/6adb417d-7241-4ee4-a70c-46a96938e0e3-014078f410/relevance/1},
isbn = {978-1-943580-57-6; ISSN 2160-9020},
year = {2019},
date = {2019-09-09},
urldate = {2019-09-09},
booktitle = {Conference on Lasers and Electro-Optics},
abstract = {We use broadband optical pump-probe spectroscopy to study coherent optical phonons in 1L-MoS2. We detect a strong coupling with the A'(1) mode, which is enhanced around the C-exciton peak. Ab-initio calculations of the phonon-induced band structure variation fully confirm this result.},
keywords = {Applied, Electric & Electronic, General Engineering, Optics, Physics},
pubstate = {published},
tppubtype = {inproceedings}
}
We use broadband optical pump-probe spectroscopy to study coherent optical phonons in 1L-MoS2. We detect a strong coupling with the A'(1) mode, which is enhanced around the C-exciton peak. Ab-initio calculations of the phonon-induced band structure variation fully confirm this result.
D (Sangalli Sangalli, D. ) ; Ferretti
Many-body perturbation theory calculations using the yambo code Journal Article
In: JOURNAL OF PHYSICS-CONDENSED MATTER, vol. 31, iss. 32, no 325902, 2019, ISSN: 0953-8984; eISSN 1361-648X.
Abstract | Links | BibTeX | Tag: Condensed matter, Physics
@article{nokey,
title = {Many-body perturbation theory calculations using the yambo code},
author = {Sangalli, D (Sangalli, D.) ; Ferretti, A (Ferretti, A.) ; Miranda, H (Miranda, H.) ; Attaccalite, C (Attaccalite, C.) ; Marri, I (Marri, I) ; Cannuccia, E (Cannuccia, E.) ; Melo, P (Melo, P.) ; Marsili, M (Marsili, M.) ; Paleari, F (Paleari, F.) ; Marrazzo, A (Marrazzo, A.) ; Prandini, G (Prandini, G.) ; Bonfà, P (Bonfa, P.) ; Atambo, MO (Atambo, M. O.) ; Affinito, F (Affinito, F.) ; Palummo, M (Palummo, M.) ; Molina-Sánchez, A (Molina-Sanchez, A.) ; Hogan, C (Hogan, C.) ; Grüning, M (Gruning, M.) ; Varsano, D (Varsano, D.) ; Marini, A (Marini, A.) },
editor = {IOP Publishing Ltd},
doi = {10.1088/1361-648X/ab15d0},
issn = {0953-8984; eISSN 1361-648X},
year = {2019},
date = {2019-08-14},
journal = {JOURNAL OF PHYSICS-CONDENSED MATTER},
volume = {31},
number = {325902},
issue = {32},
abstract = {yambo is an open source project aimed at studying excited state properties of condensed matter systems from first principles using many-body methods. As input, yambo requires ground state electronic structure data as computed by density functional theory codes such as Quantum ESPRESSO and Abinit. yambo's capabilities include the calculation of linear response quantities (both independent-particle and including electron-hole interactions), quasi-particle corrections based on the GW formalism, optical absorption, and other spectroscopic quantities. Here we describe recent developments ranging from the inclusion of important but oftneglected physical effects such as electron-phonon interactions to the implementation of a realtime propagation scheme for simulating linear and non-linear optical properties. Improvements to numerical algorithms and the user interface are outlined. Particular emphasis is given to the new and efficient parallel structure that makes it possible to exploit modern high performance computing architectures. Finally, we demonstrate the possibility to automate workflows by interfacing with the yambopy and AiiDA software tools.},
keywords = {Condensed matter, Physics},
pubstate = {published},
tppubtype = {article}
}
yambo is an open source project aimed at studying excited state properties of condensed matter systems from first principles using many-body methods. As input, yambo requires ground state electronic structure data as computed by density functional theory codes such as Quantum ESPRESSO and Abinit. yambo's capabilities include the calculation of linear response quantities (both independent-particle and including electron-hole interactions), quasi-particle corrections based on the GW formalism, optical absorption, and other spectroscopic quantities. Here we describe recent developments ranging from the inclusion of important but oftneglected physical effects such as electron-phonon interactions to the implementation of a realtime propagation scheme for simulating linear and non-linear optical properties. Improvements to numerical algorithms and the user interface are outlined. Particular emphasis is given to the new and efficient parallel structure that makes it possible to exploit modern high performance computing architectures. Finally, we demonstrate the possibility to automate workflows by interfacing with the yambopy and AiiDA software tools.
E (Perfetto Perfetto, E. ) ; Sangalli
First-Principles Nonequilibrium Green's Function Approach to Ultrafast Charge Migration in Glycine Journal Article
In: JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 15, iss. 8, pp. 4526-4534, 2019, ISSN: 1549-9618; eISSN 1549-9626.
Abstract | Links | BibTeX | Tag: Atomic and Molecular Physics, Chemistry, Physics
@article{nokey,
title = {First-Principles Nonequilibrium Green's Function Approach to Ultrafast Charge Migration in Glycine},
author = {Perfetto, E (Perfetto, E.) ; Sangalli, D (Sangalli, D.) ; Palummo, M (Palummo, M.) ; Marini, A (Marini, A.) ; Stefanucci, G (Stefanucci, G.)},
editor = {AMER CHEMICAL SOC},
doi = {10.1021/acs.jctc.9b00170},
issn = {1549-9618; eISSN 1549-9626},
year = {2019},
date = {2019-08-01},
urldate = {2019-08-01},
journal = {JOURNAL OF CHEMICAL THEORY AND COMPUTATION},
volume = {15},
issue = {8},
pages = {4526-4534},
abstract = {We investigate the photoinduced ultrafast charge migration phenomenon in the glycine molecule using a recently proposed nonequilibrium Green's functions (NEGF) approach. We first consider the dynamics resulting from the sudden removal of an electron in the valence shells, finding a satisfactory agreement with available data. Then we explicitly simulate the laser-induced photoionization process and study the evolution of the system after the pulse. We disentangle polarization and correlation effects in the electron dynamics and assign the main frequencies to specific elements of the reduced one-particle density matrix. We show that electronic correlations renormalize the bare frequencies, redistribute the spectral weights, and give rise to new spectral features.},
keywords = {Atomic and Molecular Physics, Chemistry, Physics},
pubstate = {published},
tppubtype = {article}
}
We investigate the photoinduced ultrafast charge migration phenomenon in the glycine molecule using a recently proposed nonequilibrium Green's functions (NEGF) approach. We first consider the dynamics resulting from the sudden removal of an electron in the valence shells, finding a satisfactory agreement with available data. Then we explicitly simulate the laser-induced photoionization process and study the evolution of the system after the pulse. We disentangle polarization and correlation effects in the electron dynamics and assign the main frequencies to specific elements of the reduced one-particle density matrix. We show that electronic correlations renormalize the bare frequencies, redistribute the spectral weights, and give rise to new spectral features.
G (Stefanucci Stefanucci, Gianluca) ; Marini
Non-Equilibrium Green's Functions Journal Article
In: Physical Status Solidi B-Basic Solid State Physics, vol. 256, iss. 7, no 1900335, 2019, ISSN: 0370-1972; eISSN 1521-3951.
Links | BibTeX | Tag: Condensed matter, General Physics and Astronomy
@article{nokey,
title = {Non-Equilibrium Green's Functions},
author = {Stefanucci, G (Stefanucci, Gianluca) ; Marini, A (Marini, Andrea) ; Bellucci, S (Bellucci, Stefano)},
editor = {WILEY-V C H VERLAG GMBH},
doi = {10.1002/pssb.201900335},
issn = {0370-1972; eISSN 1521-3951},
year = {2019},
date = {2019-07-01},
urldate = {2019-07-01},
journal = {Physical Status Solidi B-Basic Solid State Physics},
volume = {256},
number = {1900335},
issue = {7},
keywords = {Condensed matter, General Physics and Astronomy},
pubstate = {published},
tppubtype = {article}
}
S (Roth Roth, S. ) ; Crepaldi
Photocarrier-induced band-gap renormalization and ultrafast charge dynamics in black phosphorus Journal Article
In: 2D MATERIALS, vol. 6, iss. 3, no 031001, 2019, ISSN: 2053-1583.
Abstract | Links | BibTeX | Tag: General Materials Science, Multidisciplinary
@article{nokey,
title = {Photocarrier-induced band-gap renormalization and ultrafast charge dynamics in black phosphorus},
author = {Roth, S (Roth, S.) ; Crepaldi, A (Crepaldi, A.) ; Puppin, M (Puppin, M.) ; Gatti, G (Gatti, G.) ; Bugini, D (Bugini, D.) ; Grimaldi, I (Grimaldi, I) ; Barrilot, TR (Barrilot, T. R.) ; Arrell, CA (Arrell, C. A.) ; Frassetto, F (Frassetto, F.) ; Poletto, L (Poletto, L.) ; Chergui, M (Chergui, M.) ; Marini, A (Marini, A.) ; Grioni, M (Grioni, M.) },
editor = {OP Publishing Ltd},
doi = {10.1088/2053-1583/ab1216},
issn = {2053-1583},
year = {2019},
date = {2019-07-01},
urldate = {2019-07-01},
journal = {2D MATERIALS},
volume = {6},
number = {031001},
issue = {3},
abstract = {With its tunable band-gap and its unique optical and electronic properties black phosphorus (BP) opens exciting opportunities for optoelectronic nanotechnology. The band-gap extends from the visible to the mid-infrared spectral range, as a function of sample thickness and external parameters such as electric field and pressure. This, combined with the saturable absorption and in-plane anisotropic optical properties, makes BP a versatile platform for realizing polarization-sensitive photodetectors and absorbers. Although its near-equilibrium properties have been intensively studied, the development of efficient ultrafast optical devices requires detailed knowledge of the temporal dynamics of the photoexcited hot-carriers. Here we address the electronic response of BP to an ultrafast laser excitation, by means of time-and angle-resolved photoelectron spectroscopy. Following the optical excitation, we directly observe a shift of the valence band (VB) position, indicative of band-gap renormalization (BGR). Our data also show that the hole population in the VB relaxes with a characteristic time tau(VB) = 10.2 +/- 1.0 ps, while the lifetime of the electrons accumulated at the minimum of the conduction band is tau(CB) = 1.9 +/- 0.2 ps. The experimental results are well reproduced by ab initio calculations of the out-of-equilibrium electronic properties. Our study sets the reference for the ultrafast carrier dynamics in BP and demonstrates the material's ultrafast BGR, which is promising for optoelectronic switches.},
keywords = {General Materials Science, Multidisciplinary},
pubstate = {published},
tppubtype = {article}
}
With its tunable band-gap and its unique optical and electronic properties black phosphorus (BP) opens exciting opportunities for optoelectronic nanotechnology. The band-gap extends from the visible to the mid-infrared spectral range, as a function of sample thickness and external parameters such as electric field and pressure. This, combined with the saturable absorption and in-plane anisotropic optical properties, makes BP a versatile platform for realizing polarization-sensitive photodetectors and absorbers. Although its near-equilibrium properties have been intensively studied, the development of efficient ultrafast optical devices requires detailed knowledge of the temporal dynamics of the photoexcited hot-carriers. Here we address the electronic response of BP to an ultrafast laser excitation, by means of time-and angle-resolved photoelectron spectroscopy. Following the optical excitation, we directly observe a shift of the valence band (VB) position, indicative of band-gap renormalization (BGR). Our data also show that the hole population in the VB relaxes with a characteristic time tau(VB) = 10.2 +/- 1.0 ps, while the lifetime of the electrons accumulated at the minimum of the conduction band is tau(CB) = 1.9 +/- 0.2 ps. The experimental results are well reproduced by ab initio calculations of the out-of-equilibrium electronic properties. Our study sets the reference for the ultrafast carrier dynamics in BP and demonstrates the material's ultrafast BGR, which is promising for optoelectronic switches.
ZL (Wang Wang, Zilong) ; Molina-Sanchez
Real-time observation of the intravalley spin-flip process in single-layer WS2 Conference
EPJ Web of Conferences, vol. 205, no 05012, Cerullo, G (Cerullo, G) ; Ogilvie, J (Ogilvie, J) ; Kartner, F (Kartner, F) ; Khalil, M (Khalil, M) ; Li, R (Li, R), 2019, ISSN: 2100-014X.
Abstract | Links | BibTeX | Tag: Chemistry, Condensed matter, Mechanics, Microscopy, Optics, Physics, Spectroscopy
@conference{nokey,
title = {Real-time observation of the intravalley spin-flip process in single-layer WS2},
author = {Wang, ZL (Wang, Zilong) ; Molina-Sanchez, A (Molina-Sanchez, Alejandro) ; Altmann, P (Altmann, Patrick) ; Sangalli, D (Sangalli, Davide) ; De Fazio, D (De Fazio, Domenico) ; Soavi, G (Soavi, Giancarlo) ; Sassi, U (Sassi, Ugo) ; Bottegoni, F (Bottegoni, Federico) ; Ciccacci, F (Ciccacci, Franco) ; Finazzi, M (Finazzi, Marco) ; Wirtz, L (Wirtz, Ludger) ; Ferrari, A (Ferrari, Andrea) ; Marini, A (Marini, Andrea) ; Cerullo, G (Cerullo, Giulio) ; Dal Conte, S (Dal Conte, Stefano) },
editor = {XXI INTERNATIONAL CONFERENCE ON ULTRAFAST PHENOMENA 2018 (UP 2018)},
doi = {10.1051/epjconf/201920505012},
issn = {2100-014X},
year = {2019},
date = {2019-01-01},
urldate = {2019-01-01},
booktitle = {EPJ Web of Conferences},
volume = {205},
number = {05012},
publisher = {Cerullo, G (Cerullo, G) ; Ogilvie, J (Ogilvie, J) ; Kartner, F (Kartner, F) ; Khalil, M (Khalil, M) ; Li, R (Li, R)},
abstract = {We use helicity-resolved transient absorption spectroscopy to track intravalley scattering dynamics in monolayer WS2. We find that spin-polarized carriers scatter from upper to lower conduction band by reversing their spin orientation on a sub-ps timescale.},
keywords = {Chemistry, Condensed matter, Mechanics, Microscopy, Optics, Physics, Spectroscopy},
pubstate = {published},
tppubtype = {conference}
}
We use helicity-resolved transient absorption spectroscopy to track intravalley scattering dynamics in monolayer WS2. We find that spin-polarized carriers scatter from upper to lower conduction band by reversing their spin orientation on a sub-ps timescale.
2018
ZL (Wang Wang, Zilong) ; Molina-Sánchez
Intravalley Spin-Flip Relaxation Dynamics in Single-Layer WS2 Journal Article
In: NANO LETTERS, vol. 18, iss. 11, pp. 6882-6891, 2018, ISSN: 1530-6984; eISSN 1530-6992.
Abstract | Links | BibTeX | Tag: Chemistry, Condensed matter, General Materials Science, Multidisciplinary, Nanoscience, Nanotechnology, Physics
@article{nokey,
title = {Intravalley Spin-Flip Relaxation Dynamics in Single-Layer WS2},
author = {Wang, ZL (Wang, Zilong) ; Molina-Sánchez, A (Molina-Sanchez, Alejandro) ; Altmann, P (Altmann, Patrick) ; Sangalli, D (Sangalli, Davide) ; De Fazio, D (De Fazio, Domenico) ; Soavi, G (Soavi, Giancarlo) ; Sassi, U (Sassi, Ugo) ; Bottegoni, F (Bottegoni, Federico) ; Ciccacci, F (Ciccacci, Franco) ; Finazzi, M (Finazzi, Marco) ; Wirtz, L (Wirtz, Ludger) ; Ferrari, AC (Ferrari, Andrea C.) ; Marini, A (Marini, Andrea) ; Cerullo, G (Cerullo, Giulio) ; Dal Conte, S (Dal Conte, Stefano)},
editor = {AMER CHEMICAL SOC},
doi = {10.1021/acs.nanolett.8b02774},
issn = {1530-6984; eISSN 1530-6992},
year = {2018},
date = {2018-11-01},
urldate = {2018-11-01},
journal = {NANO LETTERS},
volume = {18},
issue = {11},
pages = {6882-6891},
abstract = {In monolayer (1L) transition metal dichalcogenides (TMDs) the valence and conduction bands are spin-split because of the strong spin-orbit interaction. In tungsten-based TMDs the spin-ordering of the conduction band is such that the so-called dark excitons, consisting of electrons and holes with opposite spin orientation, have lower energy than A excitons. The transition from bright to dark excitons involves the scattering of electrons from the upper to the lower conduction band at the K point of the Brillouin zone, with detrimental effects for the optoelectronic response of 1L-TMDs, since this reduces their light emission efficiency. Here, we exploit the valley selective optical selection rules and use two-color helicity-resolved pump-probe spectroscopy to directly measure the intravalley spin-flip relaxation dynamics in 1L-WS2. This occurs on a sub-ps time scale, and it is significantly dependent on temperature, indicative of phonon-assisted relaxation. Time-dependent ab initio calculations show that intravalley spin-flip scattering occurs on significantly longer time scales only at the K point, while the occupation of states away from the minimum of the conduction band significantly reduces the scattering time. Our results shed light on the scattering processes determining the light emission efficiency in optoelectronic and photonic devices based on 1L-TMDs.},
keywords = {Chemistry, Condensed matter, General Materials Science, Multidisciplinary, Nanoscience, Nanotechnology, Physics},
pubstate = {published},
tppubtype = {article}
}
In monolayer (1L) transition metal dichalcogenides (TMDs) the valence and conduction bands are spin-split because of the strong spin-orbit interaction. In tungsten-based TMDs the spin-ordering of the conduction band is such that the so-called dark excitons, consisting of electrons and holes with opposite spin orientation, have lower energy than A excitons. The transition from bright to dark excitons involves the scattering of electrons from the upper to the lower conduction band at the K point of the Brillouin zone, with detrimental effects for the optoelectronic response of 1L-TMDs, since this reduces their light emission efficiency. Here, we exploit the valley selective optical selection rules and use two-color helicity-resolved pump-probe spectroscopy to directly measure the intravalley spin-flip relaxation dynamics in 1L-WS2. This occurs on a sub-ps time scale, and it is significantly dependent on temperature, indicative of phonon-assisted relaxation. Time-dependent ab initio calculations show that intravalley spin-flip scattering occurs on significantly longer time scales only at the K point, while the occupation of states away from the minimum of the conduction band significantly reduces the scattering time. Our results shed light on the scattering processes determining the light emission efficiency in optoelectronic and photonic devices based on 1L-TMDs.
A (Marini Marini, Andrea) ; Pavlyukh
Functional approach to the electronic and bosonic dynamics of many-body systems perturbed with an arbitrary strong electron-boson interaction Journal Article
In: Physical Review B, vol. 98, iss. 7, no 075105, 2018, ISSN: 2469-9950; eISSN 2469-9969.
Abstract | Links | BibTeX | Tag:
@article{nokey,
title = {Functional approach to the electronic and bosonic dynamics of many-body systems perturbed with an arbitrary strong electron-boson interaction},
author = {Marini, A (Marini, Andrea) ; Pavlyukh, Y (Pavlyukh, Yaroslav)},
editor = {AMER PHYSICAL SOC},
doi = {10.1103/PhysRevB.98.075105},
issn = {2469-9950; eISSN 2469-9969},
year = {2018},
date = {2018-08-03},
urldate = {2018-08-03},
journal = {Physical Review B},
volume = {98},
number = {075105},
issue = {7},
abstract = {We present a formal derivation of the many-body perturbation theory for a system of electrons and bosons subject to a nonlinear electron-boson coupling. The interaction is treated at an arbitrary high order of bosons scattered. The considered Hamiltonian includes the well-known linear coupling as a special limit. This is the case, for example, of the Holstein and Frohlich Hamiltonians. Indeed, whereas linear coupling has been extensively studied, the scattering processes of electrons with multiple bosonic quasiparticles are largely unexplored. We focus here on a self-consistent theory in terms of dressed propagators and generalize the Hedin's equations using the Schwinger technique of functional derivatives. The method leads to an exact derivation of the electronic and bosonic self-energies, expressed in terms of a new family of vertex functions, high-order correlators, and bosonic and electronic mean-field potentials. In the electronic case we prove that the mean-field potential is the nth-order extension of the well-known Debye-Waller potential. We also introduce a bosonic mean-field potential entirely dictated by nonlinear electron-boson effects. The present scheme, treating electrons and bosons on an equal footing, demonstrates the full symmetry of the problem. The vertex functions are shown to have purely electronic and bosonic character as well as a mixed electron-boson one. These four vertex functions are shown to satisfy a generalized Bethe-Salpeter equation. Multibosons response functions are also studied and explicit expressions for the two and the three bosons case are given.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present a formal derivation of the many-body perturbation theory for a system of electrons and bosons subject to a nonlinear electron-boson coupling. The interaction is treated at an arbitrary high order of bosons scattered. The considered Hamiltonian includes the well-known linear coupling as a special limit. This is the case, for example, of the Holstein and Frohlich Hamiltonians. Indeed, whereas linear coupling has been extensively studied, the scattering processes of electrons with multiple bosonic quasiparticles are largely unexplored. We focus here on a self-consistent theory in terms of dressed propagators and generalize the Hedin's equations using the Schwinger technique of functional derivatives. The method leads to an exact derivation of the electronic and bosonic self-energies, expressed in terms of a new family of vertex functions, high-order correlators, and bosonic and electronic mean-field potentials. In the electronic case we prove that the mean-field potential is the nth-order extension of the well-known Debye-Waller potential. We also introduce a bosonic mean-field potential entirely dictated by nonlinear electron-boson effects. The present scheme, treating electrons and bosons on an equal footing, demonstrates the full symmetry of the problem. The vertex functions are shown to have purely electronic and bosonic character as well as a mixed electron-boson one. These four vertex functions are shown to satisfy a generalized Bethe-Salpeter equation. Multibosons response functions are also studied and explicit expressions for the two and the three bosons case are given.
D (Sangalli Sangalli, Davide) ; Perfetto
An ab-initio approach to describe coherent and non-coherent exciton dynamics Journal Article
In: EUROPEAN PHYSICAL JOURNAL B, vol. 91, iss. 8, no 171, 2018, ISSN: 1434-6028; eISSN 1434-6036.
Abstract | Links | BibTeX | Tag: Condensed matter, Physics
@article{nokey,
title = {An ab-initio approach to describe coherent and non-coherent exciton dynamics},
author = {Sangalli, D (Sangalli, Davide) ; Perfetto, E (Perfetto, Enrico) ; Stefanucci, G (Stefanucci, Gianluca) ; Marini, A (Marini, Andrea)},
doi = {10.1140/epjb/e2018-90126-5},
issn = {1434-6028; eISSN 1434-6036},
year = {2018},
date = {2018-08-01},
urldate = {2018-08-01},
journal = { EUROPEAN PHYSICAL JOURNAL B},
volume = {91},
number = {171},
issue = {8},
abstract = {The use of ultra-short laser pulses to pump and probe materials activates a wealth of processes which involve the coherent and non coherent dynamics of interacting electrons out of equilibrium. Non equilibrium (NEQ) many body perturbation theory (MBPT) offers an equation of motion for the density- matrix of the system which well describes both coherent and non coherent processes. In the non correlated case there is a clear relation between these two regimes and the matrix elements of the density-matrix. The same is not true for the correlated case, where the potential binding of electrons and holes in excitonic states need to be considered. In the present work we discuss how NEQ-MBPT can be used to describe the dynamics of both coherent and non-coherent excitons in the low density regime. The approach presented is well suited for an ab initio implementation.},
keywords = {Condensed matter, Physics},
pubstate = {published},
tppubtype = {article}
}
The use of ultra-short laser pulses to pump and probe materials activates a wealth of processes which involve the coherent and non coherent dynamics of interacting electrons out of equilibrium. Non equilibrium (NEQ) many body perturbation theory (MBPT) offers an equation of motion for the density- matrix of the system which well describes both coherent and non coherent processes. In the non correlated case there is a clear relation between these two regimes and the matrix elements of the density-matrix. The same is not true for the correlated case, where the potential binding of electrons and holes in excitonic states need to be considered. In the present work we discuss how NEQ-MBPT can be used to describe the dynamics of both coherent and non-coherent excitons in the low density regime. The approach presented is well suited for an ab initio implementation.
A (Seidu Seidu, Azimatu) ; Marini
Dynamical correlation effects in a weakly correlated material: Inelastic x-ray scattering and photoemission spectra of beryllium Bachelor Thesis
2018, ISSN: 2469-9950; eISSN 2469-9969.
Abstract | Links | BibTeX | Tag: Condensed matter, General Materials Science, Multidisciplinary, Physics
@bachelorthesis{nokey,
title = {Dynamical correlation effects in a weakly correlated material: Inelastic x-ray scattering and photoemission spectra of beryllium},
author = {Seidu, A (Seidu, Azimatu) ; Marini, A (Marini, Andrea) ; Gatti, M (Gatti, Matteo)},
editor = {AMER PHYSICAL SOC},
doi = {10.1103/PhysRevB.97.125144},
issn = {2469-9950; eISSN 2469-9969},
year = {2018},
date = {2018-03-26},
urldate = {2018-03-26},
journal = {Physical Review B},
volume = {97},
number = {125144},
issue = {12},
abstract = {Beryllium is a weakly correlated simple metal. Still we find that dynamical correlation effects, beyond the independent-particle picture, are necessary to successfully interpret the electronic spectra measured by inelastic x-ray scattering (IXS) and photoemission spectroscopies (PES). By combining ab initio time-dependent density-functional theory (TDDFT) and many-body Green's function theory in the GW approximation (GWA), we calculate the dynamic structure factor, the quasiparticle (QP) properties and PES spectra of bulk Be. We show that band-structure effects (i.e., due to interaction with the crystal potential) and QP lifetimes (LT) are both needed in order to explain the origin of the measured double-peak features in the IXS spectra. A quantitative agreement with experiment is obtained only when LT are supplemented to the adiabatic local-density approximation (ALDA) of TDDFT. Besides the valence band, PES spectra display a satellite, a signature of dynamical correlation due to the coupling of QPs and plasmons, which we are able to reproduce thanks to the combination of the GWA for the self-energy with the cumulant expansion of the Green's function.},
keywords = {Condensed matter, General Materials Science, Multidisciplinary, Physics},
pubstate = {published},
tppubtype = {bachelorthesis}
}
Beryllium is a weakly correlated simple metal. Still we find that dynamical correlation effects, beyond the independent-particle picture, are necessary to successfully interpret the electronic spectra measured by inelastic x-ray scattering (IXS) and photoemission spectroscopies (PES). By combining ab initio time-dependent density-functional theory (TDDFT) and many-body Green's function theory in the GW approximation (GWA), we calculate the dynamic structure factor, the quasiparticle (QP) properties and PES spectra of bulk Be. We show that band-structure effects (i.e., due to interaction with the crystal potential) and QP lifetimes (LT) are both needed in order to explain the origin of the measured double-peak features in the IXS spectra. A quantitative agreement with experiment is obtained only when LT are supplemented to the adiabatic local-density approximation (ALDA) of TDDFT. Besides the valence band, PES spectra display a satellite, a signature of dynamical correlation due to the coupling of QPs and plasmons, which we are able to reproduce thanks to the combination of the GWA for the self-energy with the cumulant expansion of the Green's function.
E (Perfetto Perfetto, E. ) ; Sangalli
Ultrafast Charge Migration in XUV Photoexcited Phenylalanine: A First-Principles Study Based on Real-Time Nonequilibrium Green's Functions Journal Article
In: JOURNAL OF PHYSICAL CHEMISTRY LETTERS, vol. 9, iss. 6, pp. 1353-1358, 2018, ISSN: 1948-7185.
Abstract | Links | BibTeX | Tag: Atomic and Molecular Physics, Chemistry, General Materials Science, Nanoscience, Nanotechnology, Physics
@article{nokey,
title = {Ultrafast Charge Migration in XUV Photoexcited Phenylalanine: A First-Principles Study Based on Real-Time Nonequilibrium Green's Functions},
author = {Perfetto, E (Perfetto, E.) ; Sangalli, D (Sangalli, D.) ; Marini, A (Marini, A.) ; Stefanucci, G (Stefanucci, G.)},
editor = {AMER CHEMICAL SOC},
doi = {10.1021/acs.jpclett.8b00025},
issn = {1948-7185},
year = {2018},
date = {2018-03-15},
urldate = {2018-03-15},
journal = {JOURNAL OF PHYSICAL CHEMISTRY LETTERS},
volume = {9},
issue = {6},
pages = {1353-1358},
abstract = {The early-stage density oscillations of the electronic charge in molecules irradiated by an attosecond XUV pulse takes place on femto- or subfemtosecond time scales. This ultrafast charge migration process is a central topic in attoscience because it dictates the relaxation pathways of the molecular structure. A predictive quantum theory of ultrafast charge migration should incorporate the atomistic details of the molecule, electronic correlations, and the multitude of ionization channels activated by the broad-bandwidth XUV pulse. We propose a first-principles nonequilibrium Green's function method fulfilling all three requirements and apply it to a recent experiment on the photoexcited phenylalanine amino acid. Our results show that dynamical correlations are necessary for a quantitative overall agreement with the experimental data. In particular, we are able to capture the transient oscillations at frequencies 0.15 and 0.30 PHz in the hole density of the amine group as well as their suppression and the concomitant development of a new oscillation at frequency 0.25 PHz after similar to 14 fs.},
keywords = {Atomic and Molecular Physics, Chemistry, General Materials Science, Nanoscience, Nanotechnology, Physics},
pubstate = {published},
tppubtype = {article}
}
The early-stage density oscillations of the electronic charge in molecules irradiated by an attosecond XUV pulse takes place on femto- or subfemtosecond time scales. This ultrafast charge migration process is a central topic in attoscience because it dictates the relaxation pathways of the molecular structure. A predictive quantum theory of ultrafast charge migration should incorporate the atomistic details of the molecule, electronic correlations, and the multitude of ionization channels activated by the broad-bandwidth XUV pulse. We propose a first-principles nonequilibrium Green's function method fulfilling all three requirements and apply it to a recent experiment on the photoexcited phenylalanine amino acid. Our results show that dynamical correlations are necessary for a quantitative overall agreement with the experimental data. In particular, we are able to capture the transient oscillations at frequencies 0.15 and 0.30 PHz in the hole density of the amine group as well as their suppression and the concomitant development of a new oscillation at frequency 0.25 PHz after similar to 14 fs.
2017
A (Molina-Sanchez Molina-Sánchez, Alejandro) ; Sangalli
Ab Initio Calculations of Ultrashort Carrier Dynamics in Two-Dimensional Materials: Valley Depolarization in Single-Layer WSe2 Journal Article
In: NANO LETTERS, vol. 17, iss. 8, pp. 4549-4555, 2017, ISSN: 1530-6984; eISSN 1530-6992.
Abstract | Links | BibTeX | Tag: Chemistry, Condensed matter, General Materials Science, Multidisciplinary, Nanoscience, Nanotechnology, Physics
@article{nokey,
title = {Ab Initio Calculations of Ultrashort Carrier Dynamics in Two-Dimensional Materials: Valley Depolarization in Single-Layer WSe2},
author = {Molina-Sánchez, A (Molina-Sanchez, Alejandro) ; Sangalli, D (Sangalli, Davide) ; Wirtz, L (Wirtz, Ludger) ; Marini, A (Marini, Andrea)},
editor = {AMER CHEMICAL SOC},
doi = {10.1021/acs.nanolett.7b00175},
issn = {1530-6984; eISSN 1530-6992},
year = {2017},
date = {2017-08-01},
urldate = {2017-08-01},
journal = {NANO LETTERS},
volume = {17},
issue = {8},
pages = {4549-4555},
abstract = {In single-layer WSe2, a paradigmatic semi-conducting transition metal dichalcogenide, a circularly polarized laser field can selectively excite electronic transitions in one of the inequivalent K-+/- valleys. Such selective valley population corresponds to a pseudospin polarization. This can be used as a degree of freedom in a "valleytronic" device provided that the time scale for its depolarization is sufficiently large. Yet, the mechanism behind the valley depolarization still remains heavily debated. Recent time-dependent Kerr experiments have provided an accurate way to visualize the valley dynamics by measuring the rotation of a linearly polarized probe pulse applied after a circularly polarized pump pulse. We present here a clear, accurate and parameter-free description of the valley dynamics. By using an atomistic, ab initio approach, we fully, disclose the elemental mechanisms that dictate the depolarization effects. Our results are in excellent agreement with recent time dependent Kerr experiments. We explain the Kerr dynamics and its temperature dependence in terms of electron-phonon-mediated processes that induce spin-flip intervalley transitions.},
keywords = {Chemistry, Condensed matter, General Materials Science, Multidisciplinary, Nanoscience, Nanotechnology, Physics},
pubstate = {published},
tppubtype = {article}
}
In single-layer WSe2, a paradigmatic semi-conducting transition metal dichalcogenide, a circularly polarized laser field can selectively excite electronic transitions in one of the inequivalent K-+/- valleys. Such selective valley population corresponds to a pseudospin polarization. This can be used as a degree of freedom in a "valleytronic" device provided that the time scale for its depolarization is sufficiently large. Yet, the mechanism behind the valley depolarization still remains heavily debated. Recent time-dependent Kerr experiments have provided an accurate way to visualize the valley dynamics by measuring the rotation of a linearly polarized probe pulse applied after a circularly polarized pump pulse. We present here a clear, accurate and parameter-free description of the valley dynamics. By using an atomistic, ab initio approach, we fully, disclose the elemental mechanisms that dictate the depolarization effects. Our results are in excellent agreement with recent time dependent Kerr experiments. We explain the Kerr dynamics and its temperature dependence in terms of electron-phonon-mediated processes that induce spin-flip intervalley transitions.
2016
Pogna, Eva A. A.; Marsili, Margherita; Fazio, Domenico De; Conte, Stefano Dal; Manzoni, Cristian; Sangalli, Davide; Yoon, Duhee; Lombardo, Antonio; Ferrari, Andrea C.; Marini, Andrea; Cerullo, Giulio; Prezzi, Deborah
Photo-Induced Bandgap Renormalization Governs the Ultrafast Response of Single-Layer MoS_2 Journal Article
In: ACS Nano, vol. 10, no 1, pp. 1182–1188, 2016, ISSN: 1936-086X.
Links | BibTeX | Tag: General Engineering, General Materials Science, General Physics and Astronomy
@article{Pogna2016,
title = {Photo-Induced Bandgap Renormalization Governs the Ultrafast Response of Single-Layer MoS_2},
author = {Eva A. A. Pogna and Margherita Marsili and Domenico De Fazio and Stefano Dal Conte and Cristian Manzoni and Davide Sangalli and Duhee Yoon and Antonio Lombardo and Andrea C. Ferrari and Andrea Marini and Giulio Cerullo and Deborah Prezzi},
doi = {10.1021/acsnano.5b06488},
issn = {1936-086X},
year = {2016},
date = {2016-01-26},
journal = {ACS Nano},
volume = {10},
number = {1},
pages = {1182–1188},
publisher = {American Chemical Society (ACS)},
keywords = {General Engineering, General Materials Science, General Physics and Astronomy},
pubstate = {published},
tppubtype = {article}
}