Time-dependent ab__initio molecular-orbital decomposition for high-harmonic generation spectroscopy

Fuente: arXiv
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Main Authors: Marchetta, Marco, Morassut, Chiara, Toulouse, Julien, Coccia, Emanuele, Luppi, Eleonora
Format: Preprint
Published: 2025
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author Marchetta, Marco
Morassut, Chiara
Toulouse, Julien
Coccia, Emanuele
Luppi, Eleonora
author_facet Marchetta, Marco
Morassut, Chiara
Toulouse, Julien
Coccia, Emanuele
Luppi, Eleonora
contents We propose a real-time time-dependent ab__initio approach within a configuration-interaction-singles ansatz to decompose the high-harmonic generation (HHG) signal of molecules in terms of individual molecular-orbital (MO) contributions. Calculations have been performed by propagating the time-dependent Schr{ö}dinger equation with complex energies, in order to account for ionization of the system, and by using tailored Gaussian basis sets for high-energy and continuum states. We have studied the strong-field electron dynamics and the HHG spectra in aligned CO2 and H2O molecules. Contribution from MOs in the strong-field dynamics depends on the interplay between the MO ionization energy and the coupling between the MO and the laser-pulse symmetries. Such contributions characterize different portions of the HHG spectrum, indicating that the orbital decomposition encodes nontrivial information on the modulation of the strong-field dynamics. Our results correctly reproduce the MO contributions to HHG for CO2 as described in the literature experimental and theoretical data and lead to an original analysis of the role of the highest occupied molecular orbitals HOMO, HOMO-1, and HOMO-2 of H2O according to the polarization direction of the laser pulse.
format Preprint
id arxiv_https___arxiv_org_abs_2512_09793
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Time-dependent ab__initio molecular-orbital decomposition for high-harmonic generation spectroscopy
Marchetta, Marco
Morassut, Chiara
Toulouse, Julien
Coccia, Emanuele
Luppi, Eleonora
Chemical Physics
We propose a real-time time-dependent ab__initio approach within a configuration-interaction-singles ansatz to decompose the high-harmonic generation (HHG) signal of molecules in terms of individual molecular-orbital (MO) contributions. Calculations have been performed by propagating the time-dependent Schr{ö}dinger equation with complex energies, in order to account for ionization of the system, and by using tailored Gaussian basis sets for high-energy and continuum states. We have studied the strong-field electron dynamics and the HHG spectra in aligned CO2 and H2O molecules. Contribution from MOs in the strong-field dynamics depends on the interplay between the MO ionization energy and the coupling between the MO and the laser-pulse symmetries. Such contributions characterize different portions of the HHG spectrum, indicating that the orbital decomposition encodes nontrivial information on the modulation of the strong-field dynamics. Our results correctly reproduce the MO contributions to HHG for CO2 as described in the literature experimental and theoretical data and lead to an original analysis of the role of the highest occupied molecular orbitals HOMO, HOMO-1, and HOMO-2 of H2O according to the polarization direction of the laser pulse.
title Time-dependent ab__initio molecular-orbital decomposition for high-harmonic generation spectroscopy
topic Chemical Physics
url https://arxiv.org/abs/2512.09793