Intersite Coulomb Interactions in Charge Ordered Systems

TL;DR

This paper uses ab initio methods to show that intersite Coulomb interactions are crucial for understanding the phases of charge ordered materials like Ba$_{1-x}$K$_x$AO$_3$, explaining various experimental phenomena.

Contribution

It demonstrates that including self-consistent nearest neighbor Hubbard interactions is essential for accurately modeling charge order phenomena in solids.

Findings

Intersite Coulomb interactions significantly influence charge ordered phases.

Self-consistent Hubbard interactions explain experimental features like phonon anomalies.

The approach provides a minimal criterion for modeling spontaneous charge orders.

Abstract

Using {\it ab initio} approaches for extended Hubbard interactions coupled to phonons, we reveal that the intersite Coulomb interaction plays important roles in determining various distinctive phases of the paradigmatic charge ordered materials of Ba$_{1-x}$K$_x A$O$_3$ ($A=$ Bi and Sb). We demonstrated that all their salient doping dependent experiment features such as breathing instabilities, anomalous phonon dispersions, and transition between charge-density wave and superconducting states can be accounted very well if self-consistently obtained nearest neighbor Hubbard interaction are included, thus establishing a minimal criterion for reliable descriptions of spontaneous charge orders in solids.