Journal Article

PreJuSER-22463

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Numerical renormalization group calculation of impurity internal energy and specific heat of quantum impurity models

Merker, L.FZJ* ; Costi, T. A.FZJ*

2012
APS College Park, Md.

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Please use a persistent id in citations: http://hdl.handle.net/2128/10846  doi:10.1103/PhysRevB.86.075150

Abstract: We introduce a method to obtain the specific heat of quantum impurity models via a direct calculation of the impurity internal energy requiring only the evaluation of local quantities within a single numerical renormalization group (NRG) calculation for the total system. For the Anderson impurity model we show that the impurity internal energy can be expressed as a sum of purely local static correlation functions and a term that involves also the impurity Green function. The temperature dependence of the latter can be neglected in many cases, thereby allowing the impurity specific heat C-imp to be calculated accurately from local static correlation functions; specifically via C-imp = partial derivative E-ionic/partial derivative T + 1/2 partial derivative E-hyb/partial derivative T, where E-ionic and E-hyb are the energies of the (embedded) impurity and the hybridization energy, respectively. The term involving the Green function can also be evaluated in cases where its temperature dependence is non-negligible, adding an extra term to C-imp. For the nondegenerate Anderson impurity model, we show by comparison with exact Bethe ansatz calculations that the results recover accurately both the Kondo induced peak in the specific heat at low temperatures as well as the high-temperature peak due to the resonant level. The approach applies to multiorbital and multichannel Anderson impurity models with arbitrary local Coulomb interactions. An application to the Ohmic two-state system and the anisotropic Kondo model is also given, with comparisons to Bethe ansatz calculations. The approach could also be of interest within other impurity solvers, for example, within quantum Monte Carlo techniques.

Keyword(s): J

Note: Record converted from VDB: 12.11.2012

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Contributing Institute(s):

1. Theoretische Nanoelektronik (PGI-2)
2. Theoretische Nanoelektronik (IAS-3)

Research Program(s):

1. Grundlagen für zukünftige Informationstechnologien (P42)

Appears in the scientific report 2012

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Database coverage:
; ; ; Current Contents - Social and Behavioral Sciences ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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