Strong-coupling expansions for the anharmonic Holstein model and for the Holstein-Hubbard model

Journal Article · Tue Oct 01 00:00:00 EDT 1996 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.54.9372· OSTI ID:390445

Freericks, J K ^[1]; Mahan, G D ^[2]

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1. Department of Physics, Georgetown University, Washington, D.C. 20057-0995 (United States)
2. Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200 (United States)

A strong-coupling expansion is applied to the anharmonic Holstein model and to the Holstein-Hubbard model through fourth order in the hopping matrix element. Mean-field theory is then employed to determine transition temperatures of the effective (pseudospin) Hamiltonian. We find that anharmonic effects are not easily mimicked by an on-site Coulomb repulsion and that anharmonicity strongly favors superconductivity relative to charge-density-wave order. Surprisingly, the phase diagram is strongly modified by relatively small values of the anharmonicity. {copyright} {ital 1996 The American Physical Society.}

• Research Organization: Oak Ridge National Laboratory
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 390445
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 13 Vol. 54; ISSN 0163-1829; ISSN PRBMDO
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ANHARMONIC OSCILLATORS
ELECTRON-PHONON COUPLING
HUBBARD MODEL
LATTICE VIBRATIONS
MEAN-FIELD THEORY
PHASE DIAGRAMS
SERIES EXPANSION
STRONG-COUPLING MODEL
SUPERCONDUCTIVITY