Ground state and excitation spectra of a strongly correlated lattice by the coupled cluster method

TL;DR

This paper develops a Spectral Coupled Cluster Method to analyze the ground state and excitation spectra of a strongly correlated lattice, successfully identifying the true ground state and resonances in a $MnO_2$ model.

Contribution

The paper introduces a novel spectral coupled cluster approach for strongly correlated lattices, enabling the detection of true ground states from nominal reference states.

Findings

Identified a negative energy resonance corresponding to the true ground state.

Demonstrated the method on a $MnO_2$ model with experimental parameter relevance.

Showed the ability to observe non-nominal symmetry ground states.

Abstract

We apply Coupled Cluster Method to a strongly correlated lattice and develop the Spectral Coupled Cluster equations by finding an approximation to the resolvent operator, that gives the spectral response for an certain class of probe operators. We apply the method to a $MnO_2$ plane model with a parameters choice which corresponds to previous experimental works and which gives a non-nominal symmetry ground state. We show that this state can be observed using our Spectral Coupled Cluster Method by probing the Coupled Cluster solution obtained from the nominal reference state. In this case one observes a negative energy resonance which corresponds to the true ground state.