First-principles perturbative computation of dielectric and Born charge tensors in finite electric fields

TL;DR

This paper develops a perturbative approach within density-functional theory to compute dielectric and Born charge tensors in insulators subjected to finite electric fields, enabling accurate response property calculations.

Contribution

It introduces a variational, perturbative method to calculate dielectric and Born effective charge tensors under finite electric fields in insulators, advancing computational capabilities.

Findings

Method successfully applied to AlAs and GaAs semiconductors.

Accurate computation of response tensors under bias fields demonstrated.

Framework extends density-functional perturbation theory to finite electric fields.

Abstract

We present a perturbative treatment of the response properties of insulating crystals under a dc bias field, and use this to study the effects of such bias fields on the Born effective charge tensor and dielectric tensor of insulators. We start out by expanding a variational field-dependent total-energy functional with respect to the electric field within the framework of density-functional perturbation theory. The second-order term in the expansion of the total energy is then minimized with respect to the first-order wave functions, from which the Born effective charge tensor and dielectric tensor are easily computed. We demonstrate an implementation of the method and perform illustrative calculations for the III-V semiconductors AlAs and GaAs under finite bias field.