# {\it Ab initio} approach to the lattice softening of an Al slab driven by collective electronic excitations after ultrashort laser pulse irradiation

## TL;DR

This study uses ab initio molecular dynamics to investigate how ultrashort laser pulses affect lattice dynamics in aluminum, revealing non-uniform plasmon screening and changes in phonon behavior.

## Contribution

It introduces a novel ab initio approach to analyze laser-induced lattice softening and plasmon effects in aluminum, advancing understanding of non-equilibrium phonon properties.

## Key findings

- Lattice distortion propagation slows with increased laser intensity.
- Harmonic force components decrease significantly under laser excitation.
- Spatially non-uniform plasmon screening influences lattice dynamics.

## Abstract

Recent advances in ultrashort laser pulse techniques have opened up a wide variety of applications in both fundamental physics and industrial fields. In this work, $ab$ $initio$ molecular dynamics simulations based on time-dependent density functional theory revealed a steady deceleration of lattice distortion propagation in an aluminum slab with increasing laser pulse intensity. Analysis of the interatomic force revealed a significant reduction in the harmonic terms and non-monotonic growth of anharmonicity. This behavior was characterized by spatially non-uniform force screening by plasmons, which is missing from Born--Oppenheimer molecular dynamics, and is consistent with the current interpretation of laser-induced periodic structure patterning. This work provides a semi-quantitative criterion for modifying the phonon properties of non-equilibrium systems.