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

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.