Collective excitations in the Penson-Kolb model: A generalized random-phase-approximation study

Journal Article · Sun Jun 01 04:00:00 EDT 1997 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.55.15506· OSTI ID:530203

Roy, G K ^[1]; Bhattacharyya, B ^[2]

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1. Solid State and Molecular Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Calcutta 700064 (India)
2. Department of Physics, Durgapur Government College, Durgapur 713214, Burdwan, West Bengal (India)

The evolution of the superconducting ground state of the half-filled Penson-Kolb model is examined as a function of the coupling constant using a mean-field approach and the generalized random phase approximation (RPA) in two and three dimensions. On-site singlet pairs hop to compete against single-particle motion in this model, giving the coupling constant a strong momentum dependence. There is a pronounced bandwidth enhancement effect that converges smoothly to a finite value in the strong-coupling (Bose) regime. The low-lying collective excitations evaluated in generalized RPA show a linear dispersion and a gradual crossover from the weak-coupling (BCS) limit to the Bose regime; the mode velocity increases monotonically in sharp contrast to the attractive Hubbard model. Analytical results are derived in the asymptotic limits. {copyright} {ital 1997} {ital The American Physical Society}

• OSTI ID: 530203
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 23 Vol. 55; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
BCS THEORY
COLLECTIVE EXCITATIONS
COUPLING
GROUND STATES
MEAN-FIELD THEORY
RANDOM PHASE APPROXIMATION
SUPERCONDUCTIVITY