An efficient implementation of high-order coupled-cluster techniques applied to quantum magnets

TL;DR

This paper presents an efficient coupled-cluster method for including multi-spin correlations in quantum spin-lattice systems, enabling accurate ground-state property calculations for square and triangular antiferromagnets.

Contribution

It introduces a systematic and efficient implementation of high-order coupled-cluster techniques for quantum magnets, improving upon previous methods.

Findings

Accurate ground-state energies for square and triangular lattices

Comparison with series expansions and quantum Monte Carlo results

Effective calculation of anisotropy susceptibility and sublattice magnetisation

Abstract

We illustrate how the systematic inclusion of multi-spin correlations of the quantum spin-lattice systems can be efficiently implemented within the framework of the coupled-cluster method by examining the ground-state properties of both the square-lattice and the frustrated triangular-lattice quantum antiferromagnets. Various physical quantities including the ground-state energy, the anisotropy susceptibility, and the sublattice magnetisation are calculated and compared with those obtained from such other methods as series expansions and quantum Monte Carlo simulations.