Development and validation of an electron temperature-dependent interaction potential for silicon and copper for the use in atomistic simulations of laser ablation

TL;DR

This paper develops and validates an electron temperature-dependent interaction potential for silicon and copper, enabling more accurate atomistic simulations of laser ablation by accounting for electronic excitation effects.

Contribution

It introduces a new electron temperature-dependent potential for copper and compares excitation effects between copper and silicon in molecular dynamics simulations.

Findings

The copper potential accurately captures electron excitation effects up to 1.2 eV.

The melting temperature variation with excitation matches predictions from free energy and phonon spectra.

Copper and silicon exhibit comparable behaviors under electronic excitation.

Abstract

Laser pulses with a duration of the order of femtoseconds lead to a strong excitation, heating and potentially to ablation of the irradiated material. During the time of strong excitation, the interaction of the atoms and thus the material dynamics can be strongly altered. To take this effect into account, an ip was developed for copper that takes the excitation of the electrons into account up to an electron temperature of 1.2 eV. Furthermore, several ways to identify non-thermal effects in Density Functional Theory calculations and how to incorporate and validate them in molecular dynamics simulations are presented. Explicitly, the free energy curves, elastic constants and phonon spectra are compared. Additionally, it is shown that the change of the melting temperature with the degree of excitation is consistent with all of these properties. Moreover, the behaviour of copper upon excitation is compared to silicon by using a similar potential that was previously developed by a different author.