Ab initio calculations of third-order elastic constants and related properties for selected semiconductors

TL;DR

This paper uses ab initio density functional theory calculations to predict third-order elastic constants for selected semiconductors, comparing results with experimental data and exploring their relation to anharmonic properties.

Contribution

It provides the first ab initio predictions of third-order elastic constants for AlN, GaN, and InN, and analyzes their connection to anharmonic material properties.

Findings

Predicted third-order elastic constants for AlN, GaN, InN.

Comparison of calculations with experimental data for Si and GaAs.

Established relations between third-order elastic constants and anharmonic behavior.

Abstract

We present theoretical studies for the third-order elastic constants $C_{ijk}$ in zinc-blende nitrides AlN, GaN, and InN. Our predictions for these compounds are based on detailed ab initio calculations of strain-energy and strain-stress relations in the framework of the density functional theory. To judge the computational accuracy, we compare the ab initio calculated results for $C_{ijk}$ with experimental data available for Si and GaAs. We also underline the relation of the third-order elastic constants to other quantities characterizing anharmonic behaviour of materials, such as pressure derivatives of the second-order elastic constants and the mode Gr\"uneisen constants for long-wavelength acoustic modes.