Simulating electronic coherences induced by conical intersections using MASH: Application to attosecond X-ray spectroscopy

TL;DR

This paper demonstrates that the MASH trajectory-based simulation method accurately predicts electronic coherences near conical intersections, outperforming standard surface hopping, and is suitable for simulating attosecond X-ray spectroscopies like TRUECARS.

Contribution

The study introduces MASH as a superior method for simulating electronic coherences in nonadiabatic dynamics, validated against quantum results and applicable to ultrafast X-ray spectroscopy.

Findings

MASH accurately captures electronic coherences near conical intersections.

Standard surface hopping can fail to describe electronic coherences.

MASH is computationally comparable to standard methods.

Abstract

In this work, we employ trajectory-based simulations to predict the electronic coherences created by nonadiabatic dynamics near conical intersections. The mapping approach to surface hopping (MASH) is compared with standard fewest-switches surface hopping on three model systems, for which the full quantum-mechanical results are available. Electronic populations and coherences in the adiabatic representation as well as nuclear densities are computed to assess the robustness of the different methods. The results show that standard surface hopping can fail to describe the electronic coherences, whereas they are accurately captured by MASH for the same computational cost. In this way, MASH appears to be an excellent simulation approach for novel X-ray spectroscopies such as the recently proposed Transient Redistribution of Ultrafast Electronic Coherences in Attosecond Raman Signals (TRUECARS).