Ab initiomodel of optical properties of two-temperature warm dense matter

Abstract

We present a model to describe thermophysical and optical properties of two-temperature systems consisted of heated electrons and cold ions in a solid lattice that occur during ultra-fast heating experiments. Our model is based on ab initio simulations within the framework of density functional theory. The optical properties are obtained by evaluating the Kubo-Greenwood formula. By applying the material parameters of our ab initio model to a two temperature model we are able to describe the temperature relaxation process of a femtosecond-laser heated gold and its optical properties within the same theoretical framework. Recent time-resolved measurements of optical properties of ultra-fast heated gold revealed the dynamics of the interaction between femtosecond laser pulses and solid state matter. Different scenarios obtained from simulations of our study are compared with experimental data. 1

Ab initio determination of effective electron–phonon coupling factor in copper

“…After obtaining the full set of | , ( )| , ( )| and 〈 2 〉| , the dependent − ℎ are calculated from Eq. (7). As seen in Fig.…”

“…On the basis of calculated 2 ( ), λ and λ〈ω 2 〉 are computed to obtain − ℎ in Eq. (7). Figure 2 and combining with Fig.…”

Density response to short‐pulse excitation in gold

“…Thus, we would have full access to the optical response of the material to any electromagnetic field once its dielectric function is known exactly. In equilibrium, this information might be obtained from ab initio simulations via the Kubo formula (see Holst et al ). However, such an approach is illusive for matter far from equilibrium.…”

Ab initioapproach to model x-ray diffraction in warm dense matter

“…For warm dense matter, i.e., states with approximately solid density and temperatures of a few electronvolts, it is particularly hard to model, as partially degenerate electrons, strong interactions, and partial ionization have to be accounted for [1]. Ab initio methods naturally include this physics, and they were directly applied to obtain macroscopic properties such as the equation of state [2,3], conductivities [4], and reflectivity [5,6]. The microscopic structure as obtained from such simulations may also be used to inform more approximate theories, e.g., the descriptions of transport and relaxation processes [7][8][9][10].…”