2023
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 | Tags: 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 | Tags: 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.
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 | Tags: 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
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 | Tags: 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.
2020
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 | Tags: 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; 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 | Tags: 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.
2019
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 | Tags: 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.
2018
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 | Tags: 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.
0000
Marini, Andrea
Dynamical electron-phonon vertex correction Journal Article Forthcoming
In: Condensed Matter, Forthcoming, ISSN: 2501.01866.
Abstract | Links | BibTeX | Tags: Atomic and Molecular Physics, Condensed matter, General Physics and Astronomy, Optics, Physics
@article{nokey,
title = {Dynamical electron-phonon vertex correction},
author = {Andrea Marini},
editor = {Cornell University},
url = {https://arxiv.org/pdf/2501.01866},
doi = { https://doi.org/10.48550/arXiv.2501.01866},
issn = {2501.01866},
journal = {Condensed Matter},
abstract = {The dynamical screening of the electron--phonon vertex is caused by the retarded oscillations of the electronic charge following the electron--hole scattering with a phonon mode. This retardation induces a frequency dependence of the electron--phonon interaction. Model Hamiltonians and {em ab--initio} approaches have instilled the idea that this retardation is, in most of the cases, negligible. In this work I demonstrate that the dynamical screening of the electron--phonon vertex cannot be neglected {em a priori}. By using a perturbative expansion I introduce a controllable and physically sound method to evaluate and include dynamical screening effects. Based on the exact results of the homogeneous electron gas I propose a dynamical vertex correction function Γe−p(ω) designed to screen the commonly used adiabatic electron--phonon interaction. This function is expressed in terms of adiabatic quantities, that can be easily calculated and used to evaluate the strength of the dynamical corrections, even in realistic materials.},
keywords = {Atomic and Molecular Physics, Condensed matter, General Physics and Astronomy, Optics, Physics},
pubstate = {forthcoming},
tppubtype = {article}
}
The dynamical screening of the electron--phonon vertex is caused by the retarded oscillations of the electronic charge following the electron--hole scattering with a phonon mode. This retardation induces a frequency dependence of the electron--phonon interaction. Model Hamiltonians and {em ab--initio} approaches have instilled the idea that this retardation is, in most of the cases, negligible. In this work I demonstrate that the dynamical screening of the electron--phonon vertex cannot be neglected {em a priori}. By using a perturbative expansion I introduce a controllable and physically sound method to evaluate and include dynamical screening effects. Based on the exact results of the homogeneous electron gas I propose a dynamical vertex correction function Γe−p(ω) designed to screen the commonly used adiabatic electron--phonon interaction. This function is expressed in terms of adiabatic quantities, that can be easily calculated and used to evaluate the strength of the dynamical corrections, even in realistic materials.
