How electrons Coulomb repulsion changes Graphene band structure

TL;DR

This paper presents a new method to analyze how electron-electron Coulomb repulsion affects graphene's electronic band structure, revealing phase transitions at specific interaction strengths.

Contribution

It introduces a novel calculation approach for realistic band structures in strongly correlated systems and applies it to graphene to identify phase transition points.

Findings

Phase transition from semi-metal to antiferromagnetic phase at u=2.596 t

Transition point shifts to u=3.2 t with inter-site correlations

Method effectively eliminates fake states in band structure calculations

Abstract

How electron-electron Coulomb repulsion modifies electronic band structure is a big change in strongly correlated systems. We introduced a method for calculation of realistic band structure of these systems and eliminating fake states. By using this method we investigated how electrons repulsion renormalizes graphene band structure. Our results show that in the dynamical mean field theory at Coulomb repulsion $u=2.596 t$ a four band semi metal to four bands anti ferro magnetism phase transition starts while due to inter site correlation for four sites, $nc=4$, effective medium super cell approximation it is $u=3.2 t$.