Finite temperature density functional theory investigation to the nonequilibrium transient warm dense state created by laser excitation

TL;DR

This study uses finite-temperature density functional theory to analyze the nonequilibrium electronic structure and electrical conductivity changes in warm dense materials like Li, Al, Cu, and Au under laser excitation, revealing orbital-specific effects.

Contribution

It provides new insights into the nonequilibrium electronic structure and conductivity of warm dense matter created by laser excitation, highlighting the role of orbital-specific phenomena.

Findings

Localized 3d states observed in Cu under inner shell hole excitation

Electrical conductivity changes depend on whether holes are in inner shell or valence bands

Finite temperature effects on electrons and ions significantly influence conductivity

Abstract

We present a finite-temperature density functional theory investigation of the nonequilibrium transient electronic structure of warm dense Li, Al, Cu, and Au created by laser excitation. Photons excite electrons either from the inner shell orbitals or from the valence bands according to the photon energy, and give rise to isochoric heating of the sample. Localized states related to the 3d orbital are observed for Cu when the hole lies in the inner shell 3s orbital. The electrical conductivity for these materials at nonequilibrium states is calculated using the Kubo-Greenwood formula. The change of the electrical conductivity, compared to the equilibrium state, is different for the case of holes in inner shell orbitals or the valence band. This is attributed to the competition of two factors: the shift of the orbital energies due to reduced screening of core electrons, and the increase of chemical potential due to the excitation of electrons. The finite temperature effect of both the electrons and the ions on the electrical conductivity is discussed in detail. This work is helpful to better understand the physics of laser excitation experiments of warm dense matter.