Nearest-Neighbor Correlations in Hubbard Model

TL;DR

This paper studies the Hubbard model using a Gutzwiller-type wave function that explicitly includes nearest-neighbor correlations, employing Kikuchi's pseudoensemble method to analyze the ground state energy and correlations for various lattice structures.

Contribution

It introduces a variational approach with explicit nearest-neighbor correlations and applies Kikuchi's pseudoensemble method to evaluate the Hubbard model at half-filling.

Findings

Ground state energy calculated for lattices with z=2,4,6 neighbors

Correlation functions explicitly determined

Method effective in large lattice limit

Abstract

The Hubbard Hamiltonian is investigated by means of a variational trial wave function of Gutzwiller's type. The wave function includes nearest - neighbor correlations in an explicit form. To calculate density matrices the method of Kikuchi's pseudoensemble is used. The case of half-filled fermionic band carefully investigated in the limit of a large number of lattice sites. The ground state energy and correlation functions are determined for lattices with z=2,4 and 6 nearest neighbors.