Ab initio calculations for the square-lattice anisotropic Heisenberg model

Bishop, R. F. and Farnell, Damian J. J. ORCID: https://orcid.org/0000-0003-0662-1927 1999. Ab initio calculations for the square-lattice anisotropic Heisenberg model. International Journal of Modern Physics B 13 (5-6) , pp. 709-719. 10.1142/S0217979299000606

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Abstract

Interest in lattice quantum spin systems as models of quantum magnets has increased with the discovery of new and interesting magnetic materials. Here we use a well-known technique of quantum many-body theory, namely the coupled-cluster method (CCM), to investigate the nearest-neighbour, spin-½, anisotropic Heisenberg model on the square lattice. Ground-state expectation values for quantities such as the ground-state energy and the sublattice magnetisation are determined to an accuracy comparable with that of the best of other available techniques including Monte Carlo methods. In order to demonstrate this point we present results for various values of the anisotropy parameter, including those for the isotropic Heisenberg model and the isotropic XY model. We show that it is now possible to determine the presence and position of the quantum phase transitions using ab initio CCM calculations, and furthermore that we can accurately predict the critical behaviour at these points.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Dentistry
Subjects:	Q Science > QC Physics
Publisher:	World Scientific Publishing
ISSN:	0217-9792
Last Modified:	04 Jan 2024 08:41
URI:	https://orca.cardiff.ac.uk/id/eprint/64294

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