A self-consistent perturbative evaluation of ground state energies: application to cohesive energies of spin lattices

TL;DR

This paper introduces a perturbative, self-consistent method for estimating ground state energies from a single reference, yielding accurate cohesive energies and aiding phase transition analysis in spin lattices.

Contribution

It presents a novel, simplified formalism that combines perturbation theory with a coupled cluster-like approach for efficient ground state energy estimation.

Findings

Accurately predicts cohesive energies of spin lattices.

Provides simple analytic solutions for model Hamiltonians.

Effectively locates phase transitions in spin systems.

Abstract

The work presents a simple formalism which proposes an estimate of the ground state energy from a single reference function. It is based on a perturbative expansion but leads to non linear coupled equations. It can be viewed as well as a modified coupled cluster formulation. Applied to a series of spin lattices governed by model Hamiltonians the method leads to simple analytic solutions. The so-calculated cohesive energies are surprisingly accurate. Two examples illustrate its applicability to locate phase transition.