CPA for charge ordering in the extended Hubbard model

TL;DR

This paper investigates charge ordering in the extended Hubbard model using CPA, revealing how Coulomb interactions influence phase boundaries and discovering reentrant transitions at finite temperatures.

Contribution

It introduces a CPA-based analysis of charge ordering in the extended Hubbard model, highlighting the critical role of inter-site Coulomb repulsion V.

Findings

Charge ordering exists only if V exceeds a critical value proportional to t.

Reentrant phase transition occurs at finite temperatures in certain V regions.

Charge order phase boundary depends on U and V parameters.

Abstract

We study charge ordering in the extended Hubbard model with both on-site and nearest neighbor Coulomb repulsion (U and V, respectively) within the Coherent potential approximation (CPA). The phase boundary between the homogeneous and charge ordered phase for the square lattice is obtained for different values of U. It is shown that at quarter filling for all values of U the charge ordering exists only if the inter-site Coulomb repulsion V exceeds certain critical value which is of the order of the kinetic energy t. At finite temperature a reentrant transition is found in some region of V.