Ground State of Strongly Correlated Fermions: Short-Range Order
Abstract
A new variational method is developed to calculate the ground state energy of Fermi systems with strong short-range correlations. A trial wave function of Gutzwiller's type contains additional variational parameters corresponding to configurations of pairs of nearest-neighbor sites. To evaluate the ground state energy, generalized Kikuchi's pseudo-ensemble method is used. The Hubbard model at half band-filling is investigated. The ground state energy of the paramagnetic phase is calculated for a chain, square and simple cubic lattices. It is shown that the short-range order lowers drastically the ground state energy of the Hubbard model at intermediate interaction strength. The paramagnetic phase of the Kondo-Hubbard model ($S=1/2$ and $S=5/2$) at half band-filling is investigated. The ground state energy, correlation functions and effective mass are calculated for chain, square and simple cubic lattices. A quantum phase transition was found for simple cubic lattice.
- Publication:
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arXiv e-prints
- Pub Date:
- December 2000
- DOI:
- 10.48550/arXiv.cond-mat/0012018
- arXiv:
- arXiv:cond-mat/0012018
- Bibcode:
- 2000cond.mat.12018K
- Keywords:
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- Condensed Matter - Strongly Correlated Electrons
- E-Print:
- RevTex,10 pages, 7 figures, 3 tables