Ehrenfest dynamics implemented in the all-electron package exciting

TL;DR

This paper presents the implementation of Ehrenfest dynamics within the all-electron package exciting, enabling real-time simulation of non-adiabatic molecular dynamics and electronic excitations under laser pulses.

Contribution

The work introduces Ehrenfest dynamics into the exciting package, expanding its capabilities for real-time non-adiabatic molecular simulations with validation against Octopus.

Findings

Good agreement with Octopus code in test cases

Successful simulation of laser-induced excitations in cubic BN

Demonstrated relaxation of diamond and cubic BN after lattice distortion

Abstract

Ehrenfest Dynamics combined with real-time time-dependent density functional theory has proven to be a reliable tool to study non-adiabatic molecular dynamics with a reasonable computational cost. Among other possibilities, it allows for assessing in real time electronic excitations generated by ultra-fast laser pulses, as e.g., in pump-probe spectroscopy, and their coupling to the nuclear vibrations even beyond the linear regime. In this work, we present its implementation in the all-electron full-potential package exciting. Three cases are presented as examples: diamond and cubic BN relaxed after an initial lattice distortion, and cubic BN exposed to a laser pulse. Comparison with the Octopus code exhibits good agreement.