Quantum Monte Carlo simulations of the degenerate single-impurity Anderson model

Journal Article · Sat May 15 04:00:00 EDT 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.47.13137· OSTI ID:6787996

Bonca, J; Gubernatis, J E ^[1]

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1. Theoretical Divison and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

We present results of quantum Monte Carlo simulations of the degenerate, single-impurity, Anderson model. Using maximum-entropy methods, we performed the analytic continuation of the imaginary-time Green's functions produced by these simulations to obtain their real-frequency, single-particle, spectral densities for degeneracies of [ital N]=2, 4, and 6. Incorporating higher degeneracies into the model enables us, on the one hand, to compare Monte Carlo results with the self-consistent large-[ital N] approximation (NCA) and numerical-renormalization-group calculations (NGR) and, on the other hand, to bring the models closer to the physical systems. The low temperatures reached in our calculations are comparable to, or even lower than, the corresponding Kondo temperatures. The NCA and NRG calculations were found to show qualitatively good agreement with our results: the Kondo temperature increases with increasing degeneracy, and the amplitude of the side peaks in the spectral density decreases as degeneracy increases while the half-width of these peaks increases.

• OSTI ID: 6787996
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 47:20; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ALLOYS
CALCULATION METHODS
DILUTE ALLOYS
ELECTRONIC STRUCTURE
FUNCTIONS
GREEN FUNCTION
IMPURITIES
KONDO EFFECT
MAGNETIC PROPERTIES
MECHANICS
MONTE CARLO METHOD
PHYSICAL PROPERTIES
QUANTUM MECHANICS