Single and many particle correlation functions and uniform phase bases for strongly correlated systems

Castleton, CWM ORCID: https://orcid.org/0000-0001-6790-6569 and Long, MW, 1997. Single and many particle correlation functions and uniform phase bases for strongly correlated systems. Journal of Physics: Condensed Matter, 9 (36), pp. 7563-7582. ISSN 0953-8984

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Abstract

The need for suitable many or infinite fermion correlation functions to describe strongly correlated systems is discussed, and the question linked to the need for a correlated basis, in which the ground state may be positive definite for certain low dimensional geometries. In seeking a positive definite basis a particular trial basis is proposed, based on that for hard core bosons in pure one dimensional systems. Single particle correlations in this basis are evaluated for the case of the g round state of a quasi-1D Hubbard in the limit of extreme correlation. The model is a st rip of the 2D square lattice wrapped around a cylinder, and is related to a ladder geometry with periodic boundary conditions along it’s edges. This is done using both a novel mean field theory and exact diagonalisation, and the basis is indeed found to be well suited for examining (quasi)- order in the model. The model has a paramagnetic region and a Nagaoka ferromagnetic region. In the numerical calculation the correlation funct ion in the paramagnetic phase has power law decay and the charge motion is qualitatively ha rd core bosonic. The mean field leads to an example of a BCS type model with single particle bosonic long range order.

Item Type:	Journal article
Publication Title:	Journal of Physics: Condensed Matter
Creators:	Castleton, C.W.M. and Long, M.W.
Publisher:	IOP Publishing
Date:	30 June 1997
Volume:	9
Number:	36
ISSN:	0953-8984
Identifiers:	Number Type 10.1088/0953-8984/9/36/005 DOI
Divisions:	Schools > School of Science and Technology
Record created by:	EPrints Services
Date Added:	09 Oct 2015 10:08
Last Modified:	09 Jun 2017 13:19
URI:	https://irep.ntu.ac.uk/id/eprint/8196

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