Configuration dependence of physical properties of a ferroelectric solid solution

TL;DR

This paper investigates how different atomic configurations in a ferroelectric solid solution affect its physical properties, aiming to improve first-principles modeling of these materials.

Contribution

It provides a detailed comparison of physical properties across configurations and highlights the significance of second-neighbor effects in ferroelectric behavior.

Findings

Second-neighbor interactions significantly influence physical properties.

Symmetry-preserving relaxations impact polar instabilities.

Cluster expansions reveal key effects on dielectric and piezoelectric properties.

Abstract

In this article, we motivate the detailed comparison of the physical properties of individual configurations of a ferroelectric solid solution as a means toward developing first principles models for these systems. We compare energies, dielectric constants epsilon_infinity, mode effective charges of local polar distortions, and the zero temperature piezoelectric behavior of several ordered Pb_3GeTe_4 supercells. Cluster expansions of these properties show the importance of second-neighbor effects, which can be related to symmetry-preserving relaxation and its effect on the symmetry breaking polar instabilities.