Condensed Matter Physics, 2015, vol. 18, No. 3, 33003
DOI:10.5488/CMP.18.33003           arXiv:1510.06531

Title: The β-expansion of the D=1 fermionic spinless Hubbard model off the half-filling regime
  E.V. Correa Silva ( Departamento de Matematica, Fisica e Computacao, Faculdade de Tecnologia, Universidade do Estado do Rio de Janeiro, Rodovia Presidente Dutra km 298 s/n, Polo Industrial, CEP 27537-000, Resende-RJ, Brazil) ,
  M.T. Thomaz ( Instituto de Fisica, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza s/n, CEP 24210-346, Niteoi-RJ, Brazil ) ,
  O. Rojas ( Departamento de Fisica, Universidade Federal de Lavras, Caixa Postal 3037, CEP 37200-000, Lavras-MG, Brazil )

We obtain that when the spinless model is off the half-filling regime (μ ≠ V), the Helmholtz free energy (HFE) can be written as two β-expansions: one expansion comes from the half-filling configuration and another one that depends on the parameter x = μ - V. We show numerically that the chemical potential as a function of temperature satisfies a relation similar to one derived from the particle-hole symmetry of the fermionic spinless model. We extend the β-expansion of the HFE of the one-dimensional fermionic spinless Hubbard model up to order β8.

Key words: quantum statistical mechanics, strongly correlated electron system, spin chain models
PACS: 05.30.Fk, 71.27.+a, 75.10.Pq

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