Coupling of electrons to the electromagnetic field in a localized basis

TL;DR

This paper presents a straightforward formula for coupling electrons to electromagnetic fields in complex systems, incorporating intra-atomic excitations and nuclear motion, enabling advanced simulations of electron-nuclear dynamics under ultrashort laser pulses.

Contribution

It introduces a new, simple coupling formula that enhances first-principles simulations of electron and nuclear dynamics in materials and molecules.

Findings

Includes intra-atomic excitations and nuclear motion in coupling calculations

Applicable to ultrashort laser pulse response simulations

Discusses potential of reduced Ehrenfest methods for nonadiabatic dynamics

Abstract

A simple formula is obtained for coupling electrons in a complex system to the electromagnetic field. It includes the effect of intra-atomic excitations and nuclear motion, and can be applied in. e.g., first-principles-based simulations of the coupled dynamics of electrons and nuclei in materials and molecules responding to ultrashort laser pulses. Some additional aspects of nonadiabatic dynamical simulations are also discussed, including the potential of "reduced Ehrenfest'" simulations for treating problems where standard Ehrenfest simulations will fail.