First-principles theory and calculation of flexoelectricity

TL;DR

This paper presents a comprehensive first-principles framework for calculating flexoelectric and piezoelectric tensors, enabling direct computation from density-functional theory including electronic and lattice effects, with practical supercell methods demonstrated on various cubic insulators.

Contribution

It introduces a unified first-principles theory and supercell-based computational methods for flexoelectricity, applicable to a wide range of insulating materials.

Findings

Successfully computed flexoelectric coefficients for multiple cubic insulators.

Demonstrated the practical applicability of the methods in density-functional calculations.

Provided a general approach for including electronic and lattice contributions in flexoelectric tensors.

Abstract

We develop a general and unified first-principles theory of piezoelectric and flexoelectric tensor, formulated in such a way that the tensor elements can be computed directly in the context of density-functional calculations, including electronic and lattice contributions. We introduce a practical supercell-based methods for calculating the flexoelectric coefficients from first principles, and demonstrate them by computing the coefficients for a variety of cubic insulating materials, including C, Si, MgO, NaCl, CsCl, BaZrO3, BaTiO3, PbTiO3 and SrTiO3.