Transition pressures and enthalpy barriers for the cd->beta-tin transition in Si and Ge under non-hydrostatic conditions

TL;DR

This study uses ab-initio methods to analyze the phase transition from cd to beta-tin in silicon and germanium under various pressure conditions, introducing a new approach to account for non-hydrostatic effects on transition pressures and barriers.

Contribution

A novel computational method to evaluate the effects of non-hydrostatic pressure on phase transition pressures and enthalpy barriers in Si and Ge.

Findings

Good agreement with experimental data

New method accurately predicts non-hydrostatic effects

Provides detailed insights into phase transition mechanisms

Abstract

We present an ab-initio study of the phase transition cd->beta-tin in Si and Ge under hydrostatic and non-hydrostatic pressure. For this purpose we have developed a new method to calculate the influence of non-hydrostatic pressure components not only on the transition pressure but also on the enthalpy barriers between the phases. We find good agreement with available experimental and other theoretical data. The calculations have been performed using the plane-wave pseudopotential approach to the density-functional theory within the local-density and the generalized-gradient approximation implemented in VASP.