Metric wave approach to flexoelectricity within density functional perturbation theory

Abstract

The first-principles theory of flexoelectricity, the electric polarization appearing in response to a strain gradient, has matured considerably in recent years, but some conceptual and technical issues have remained. To address these, the authors present here a novel linear-response approach based on a metric-wave formulation, in which an acoustic phonon is regarded as a geometric distortion of a curvilinear frame of reference while the atomic coordinates remain fixed in this frame. Through careful implementation and testing, the researchers demonstrate that this approach greatly facilitates the calculation of flexoelectric and related responses to inhomogeneous deformations in crystalline materials.