2008/04/08 by Jakub Jȩdrak, Jȩdrak, Jakub, Jozef Spałek +1
Physics and Astronomy · #FOS: Physical sciences #Statistical Mechanics (cond-mat.stat-mech) #Strongly Correlated Electrons (cond-mat.str-el) #cond-mat.stat-mech #cond-mat.str-el
paper · pdf · doi:10.48550/arxiv.0804.1376
20 pages, text has been revised and extended, typos fixed
arxiv created 2009/09/01 · arxiv updated 2009/12/01
We analyze a class of mean-field (MF) lattice-fermion Hamiltonians and construct the corresponding grand-canonical density operator for such system. New terms are introduced, which may be interpreted as local fugacities, molecular fields, etc. The presence of such terms is an unavoidable consequence of a consistent statistical description. Although in some cases (e.g. in the Hartree or the Hartree-Fock-type approximation) the presented formalism is redundant, in general (e.g. for a renormalized t-J model) it leads to nontrivial modifications of the thermodynamic properties.