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Variational pair theory of the attractive and extended Hubbard model ind-dimensions
- Source :
- Zeitschrift f�r Physik B Condensed Matter. 93:219-238
- Publication Year :
- 1994
- Publisher :
- Springer Science and Business Media LLC, 1994.
-
Abstract
- We present a variational approach for treating the Hubbard Hamiltonian in one, two and three dimensions. It is based on 2M-fermion wavefunctions which are allowed to form correlated spin-singlet pairs. Expressions for the ground state energy and correlation functions are derived in terms of general pair coefficient functions. The presented approach offers a convenient starting point for improved variational treatments that allow to include different specific types of pair correlations. We present first applications to the attractive and to the extended Hubbard model using a very simple ansatz for the pair coefficient functions. The ground state energy, chemical potential, order parameter, momentum distribution as well as spin-spin and density-density correlation functions follow from a system of coupled nonlinear equations that has to be solved selfconsistently. All quantities are given for arbitrary band-filling in one, two and three dimensions. Our results are compared with those of other approximations and for the one-dimensional case with the exact results of Krivnov and Ovchinnikov.
- Subjects :
- Physics
Hubbard model
Fermion
Condensed Matter Physics
Electronic, Optical and Magnetic Materials
symbols.namesake
Nonlinear system
Quantum mechanics
symbols
Condensed Matter::Strongly Correlated Electrons
General Materials Science
Fundamental Resolution Equation
Wave function
Hamiltonian (quantum mechanics)
Ground state
Mathematical physics
Ansatz
Subjects
Details
- ISSN :
- 14346036 and 07223277
- Volume :
- 93
- Database :
- OpenAIRE
- Journal :
- Zeitschrift f�r Physik B Condensed Matter
- Accession number :
- edsair.doi...........6fc15be4059e8449194b4f937460ed4f