Electron localization : band-by-band decomposition, and application to oxides

TL;DR

This paper develops a band-by-band decomposition method for electron localization length in oxides using density functional theory, and applies it to various materials to analyze ferroelectric phase transitions and related properties.

Contribution

It introduces a new band-by-band decomposition approach for electron localization length, clarifies its interpretation with Wannier functions, and applies it to study oxides and ferroelectric transitions.

Findings

Decomposition of localization length into bands reveals detailed electronic structure.

Localization tensor varies during ferroelectric phase transitions.

Relationship established between localization tensor and Born effective charges.

Abstract

Using a plane wave pseudopotential approach to density functional theory we investigate the electron localization length in various oxides. For this purpose, we first set up a theory of the band-by-band decomposition of this quantity, more complex than the decomposition of the spontaneous polarization (a related concept), because of the interband coupling. We show its interpretation in terms of Wannier functions and clarify the effect of the pseudopotential approximation. We treat the case of different oxides: BaO, $\alpha$-PbO, BaTiO$_3$ and PbTiO$_3$. We also investigate the variation of the localization tensor during the ferroelectric phase transitions of BaTiO$_3$ as well as its relationship with the Born effective charges.