Orbital-free extension to Kohn-Sham density functional theory equation of state calculations: application to silicon dioxide

TL;DR

This paper introduces an orbital-free DFT approach to extend Kohn-Sham DFT for high-temperature SiO₂ equation of state calculations, achieving good agreement with experimental shock data and providing a new EOS table.

Contribution

A novel orbital-free DFT formulation that seamlessly extends Kohn-Sham DFT to high-temperature regimes for SiO₂, enabling accurate EOS calculations.

Findings

Excellent agreement with experimental shock data

Successful construction of a new SiO₂ EOS table

Validated orbital-free DFT approach for high-temperature regimes

Abstract

The liquid regime equation of state of silicon dioxide SiO$_2$ is calculated via quantum molecular dynamics in the density range 5 to 15 g/cc and with temperatures from 0.5 to 100 eV, including the $\alpha$-quartz and stishovite phase Hugoniot curves. Below 8 eV calculations are based on Kohn-Sham density functional theory (DFT), above 8 eV a new orbital-free DFT formulation, presented here, based on matching Kohn-Sham DFT calculations is employed. Recent experimental shock data is found to be in very good agreement with the current results. Finally both experimental and simulation data are used in constructing a new liquid regime equation of state table for SiO$_2$.