Ground state energy of the Hubbard model: cluster-perturbative results

TL;DR

This paper introduces a hybrid approach combining exact diagonalization of small clusters with perturbative methods to efficiently estimate the ground state energy of the Hubbard model, addressing limitations of system size in numerical solutions.

Contribution

It presents a novel cluster-perturbative method that extends the applicability of exact diagonalization to larger systems in the Hubbard model.

Findings

Effective estimation of ground state energy for larger clusters

Improved accuracy over purely perturbative methods

Potential for scalable calculations in strongly correlated systems

Abstract

When electron correlations are important it is often necessary to use numerical methods to solve the Hamiltonian for a finite system (cluster) "exactly". Unfortunately, such methods are restricted to small systems. We propose to combine the "exact" numerical diagonalization for small clusters with the perturbative calculations to take into account the intracluster as well as intercluster interactions.