Transport and optical properties of warm dense aluminum in the two-temperature regime: Ab initio calculation and semiempirical approximation

TL;DR

This study investigates the transport and optical properties of warm dense liquid aluminum in the two-temperature regime using ab initio calculations and develops a semiempirical approximation that aligns with the Drude model.

Contribution

The paper provides the first ab initio calculations of optical and transport properties of warm dense aluminum in the two-temperature regime and introduces a semiempirical model based on these results.

Findings

The semiempirical approximation accurately describes conductivity and thermal conductivity dependences.

Results support models with relaxation time decreasing as T_i^{-0.25}.

The findings are consistent with the Drude model with an effective relaxation time.

Abstract

This work is devoted to the investigation of transport and optical properties of liquid aluminum in the two-temperature case. At first optical properties, static electrical and thermal conductivities were obtained in the \textit{ab initio} calculation. The \textit{ab initio} calculation is based on the quantum molecular dynamics, density functional theory and the Kubo-Greenwood formula. The semiempirical approximation was constructed based on the results of the \textit{ab initio} caculation. The approximation yields the dependences $\sigma_{1_\mathrm{DC}}\propto1/T_i^{0.25}$ and $K\propto T_e/T_i^{0.25}$ for the static electrical conductivity and thermal conductivity, respectively. The approximation is valid for liquid aluminum at $\rho=2.70$~g/cm$^3$, 3~kK~$\leq T_i\leq T_e\leq20$~kK. Our results are well described by the Drude model with the effective relaxation time $\tau\propto T_i^{-0.25}$. We have compared our results with a number of other models. They are all reduced in the low-temperature limit to the Drude model with different expressions for the relaxation time $\tau$. Our results are not consistent with the models in which $\tau\propto T_i^{-1}$ and support the models which use the expressions with the slower decrease of the relaxation time.