Exact Diagonalization Study of 2D Hubbard Model on Honeycomb Lattice: Semi-metal-Insulator Transition

TL;DR

This study uses exact diagonalization dynamical mean field theory to analyze the semi-metal to insulator phase transition in the 2D Hubbard model on a honeycomb lattice at zero temperature, revealing a second-order transition.

Contribution

It provides a detailed analysis of the phase transition in the honeycomb lattice Hubbard model using exact diagonalization DMFT, identifying the critical interaction and transition nature.

Findings

Semi-metal phase at weak interactions

Second-order phase transition to insulator

Critical interaction value determined

Abstract

Phase transition in a honeycomb lattice is studied by the means of the two dimensional Hubbard model and the exact diagonalization dynamical mean field theory at zero temperature. At low energies, the dispersion relation is shown to be a linear function of the momentum. In the limit of weak interactions, the system is in the semi-metal phase. By increasing the on site interaction a semi-metal to insulator transition takes place in the paramagnetic phase. Calculation of double occupancy shows such a phase transition is of the second order. The respective phase transition point and critical on-site interaction are determined using renormalized Fermi velocity factor.