Ab initio calculation of the shock Hugoniot of bulk silicon

TL;DR

This paper introduces an efficient ab initio method to calculate the shock Hugoniot of bulk silicon, accounting for phase transitions and yielding, and validates it against experimental data.

Contribution

It presents a novel annealing procedure combined with ab initio molecular dynamics to determine the shock Hugoniot locus in silicon, including phase transitions and plastic yielding effects.

Findings

Results agree well with experimental data

Method effectively captures phase transitions under shock

Provides detailed Hugoniot states for silicon up to 70 GPa

Abstract

We describe a simple annealing procedure to obtain the Hugoniot locus (states accessible by a shock wave) for a given material in a computationally efficient manner. We apply this method to determine the Hugoniot locus in bulk silicon from ab initio molecular dynamics with forces from density-functional theory, up to 70 GPa. The fact that shock waves can split into multiple waves due to phase transitions or yielding is taken into account here by specifying the strength of any preceding waves explicitly based on their yield strain. Points corresponding to uniaxial elastic compression along three crystal axes and a number of post-shock phases are given, including a plastically-yielded state, approximated by an isotropic stress configuration following an elastic wave of predetermined strength. The results compare well to existing experimental data for shocked silicon.