Simulation of Resonance Raman X-Ray Scattering Signals from Nonadiabatic Quantum Dynamics. Approximated Protocols in the Limit of Short Lifetimes of Core-Excited States
5 affiliations
- 1Dipartimento di Chimica Industriale "Toso Montanari", Universita di Bologna - Alma Mater Studiorum, Via Piero Gobetti 85, 40129 Bologna, Italy
- 2Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
- 3Theoretical Chemistry and Molecular Physics Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
- 4Department of Chemistry and Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
- 5Consiglio Nazionale delle Ricerche, Istituto di Chimica dei Composti Organo Metallici (ICCOM-CNR), I-56124 Pisa, Italy
Abstract
Time-resolved resonant inelastic X-ray scattering (RIXS) provides a sensitive probe of photoinduced nonadiabatic dynamics. Its direct simulation, however, is computationally demanding, as it formally requires nested loops of nuclear wave-packet propagation on the coupled valence states and on the core-excited states. Here, we derive a hierarchy of computationally efficient approximations to the time-dependent RIXS signal by exploiting the separation of timescales between the ultrashort core-hole lifetime and the slower nuclear and electronic dynamics. Starting from the nonstationary generalization of the Kramers-Heisenberg expression, we approximate the Raman transition operator through short-time expansions of the intermediate-state propagators, replacing explicit propagation on the core-excited manifold by instantaneous expectation values of valence-to-core energy gaps. We further derive first- and second-order approximations for the scattering correlation function in terms of the evolving valence-state population and low-order moments of the valence-state energy gap. In the energy-gain region, the resulting RIXS signal reduces to closed-form lineshape functions whose positions follow the time-dependent valence-state energy gaps and whose intensities track the population of the upper valence state. The proposed formulation therefore reduces time-resolved RIXS simulations to an inexpensive post-processing of nonadiabatic quantum dynamics while retaining a direct connection between the signal and the underlying electronic and nuclear dynamics.
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BibTeX
@misc{montorsi2026simulation,
title = {{Simulation of Resonance Raman X-Ray Scattering Signals from Nonadiabatic Quantum Dynamics. Approximated Protocols in the Limit of Short Lifetimes of Core-Excited States}},
author = {Francesco Montorsi and Mohammad Aarabi and Niranjan Govind and Sergei Tretiak and Shaul Mukamel and Fabrizio Santoro and MARCO GARAVELLI},
howpublished = {Zenodo},
year = {2026},
month = oct,
doi = {10.5281/zenodo.23511447},
url = {https://zenodo.org/records/23511447},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Simulation of Resonance Raman X-Ray Scattering Signals from Nonadiabatic Quantum Dynamics. Approximated Protocols in the Limit of Short Lifetimes of Core-Excited States
AU - Francesco Montorsi
AU - Mohammad Aarabi
AU - Niranjan Govind
AU - Sergei Tretiak
AU - Shaul Mukamel
AU - Fabrizio Santoro
AU - MARCO GARAVELLI
PY - 2026
DA - 2026/10/20
PB - Zenodo
DO - 10.5281/zenodo.23511447
UR - https://zenodo.org/records/23511447
AB - Time-resolved resonant inelastic X-ray scattering (RIXS) provides a sensitive probe of photoinduced nonadiabatic dynamics. Its direct simulation, however, is computationally demanding, as it formally requires nested loops of nuclear wave-packet propagation on the coupled valence states and on the core-excited states. Here, we derive a hierarchy of computationally efficient approximations to the time-dependent RIXS signal by exploiting the separation of timescales between the ultrashort core-hole lifetime and the slower nuclear and electronic dynamics. Starting from the nonstationary generalization of the Kramers-Heisenberg expression, we approximate the Raman transition operator through short-time expansions of the intermediate-state propagators, replacing explicit propagation on the core-excited manifold by instantaneous expectation values of valence-to-core energy gaps. We further derive first- and second-order approximations for the scattering correlation function in terms of the evolving valence-state population and low-order moments of the valence-state energy gap. In the energy-gain region, the resulting RIXS signal reduces to closed-form lineshape functions whose positions follow the time-dependent valence-state energy gaps and whose intensities track the population of the upper valence state. The proposed formulation therefore reduces time-resolved RIXS simulations to an inexpensive post-processing of nonadiabatic quantum dynamics while retaining a direct connection between the signal and the underlying electronic and nuclear dynamics.
ER -