Topologically correct phase boundaries and transition temperatures for Ising Hamiltonians via self-consistent coarse-grained cluster-lattice models

Thumbnail Image
Date
2011-04-01
Authors
Tan, Teck
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract

We derive a cluster mean-field theory for an Ising Hamiltonian using a cluster-lattice Fourier transform with a cluster of size Nc and a coarse-grained (CG) lattice into cells of size Ncell. We explore forms with Ncell⩾Nc, including a non-CG (NCG) version with Ncell→∞. For Nc=Ncell, the set of static, self-consistent equations relating cluster and CG lattice correlations is analogous to that in dynamical cluster approximation and cellular dynamical mean-field theory used in correlated electron physics. A variational Nc-site cluster grand potential based on Nc=Ncell CG lattice maintains thermodynamic consistency and improves predictions, recovering Monte Carlo and series expansion results upon finite-size scaling; notably, the Nc=1 CG results already predict well the first- and second-order phase boundary topology and transition temperatures for frustrated lattices. The NCG version is significantly faster computationally than the CG case and more accurate at fixed Nc for ferromagnetism, which is potentially useful for cluster expansion and quantum cluster applications.

Series Number
Journal Issue
Is Version Of
Versions
Series
Academic or Administrative Unit
Type
article
Comments

This article is from Phys. Rev. B 83, 144427 (2011), doi:10.1103/PhysRevB.83.144427. Posted with permission.

Rights Statement
Copyright
Sat Jan 01 00:00:00 UTC 2011
Funding
DOI
Supplemental Resources
Collections