Influence of rotational instability on the polarization structure of SrTiO3

TL;DR

This study investigates how rotational instability affects the polarization structure of SrTiO3 using first-principles calculations, revealing the sensitivity of polarization to structural distortions and providing insights into microscopic interactions.

Contribution

It rigorously proves the existence of folding effects in polarization structure and demonstrates the impact of oxygen-octahedra rotation on polarization and Wannier-function interactions.

Findings

Folding effect in polarization structure confirmed both numerically and analytically.

Polarization structure remains significantly different with rotational instability after removing folding effects.

Microscopic Wannier-function interactions vary notably with oxygen-octahedra rotation.

Abstract

The k-space polarization structure and its strain response in SrTiO3 with rotational instability are studied using a combination of first-principles density functional calculations, modern theory of polarization, and analytic Wannier-function formulation. (1) As one outcome of this study, we rigorously prove-both numerically and analytically-that folding effect exists in polarization structure. (2) After eliminating the folding effect, we find that the polarization structure for SrTiO3 with rotational instability is still considerably different from that for non-rotational SrTiO3, revealing that polarization structure is sensitive to structure distortion of oxygen-octahedra rotation and promises to be an effective tool for studying material properties. (3) Furthermore, from polarization structure we determine the microscopic Wannier-function interactions in SrTiO3. These interactions are found to vary significantly with and without oxygen-octahedra rotation.