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KR: Fachgruppe Kristallographie
KR 5: Poster I – including Multiferroics (MA with DF, DS, KR, TT)
KR 5.48: Poster
Dienstag, 27. März 2012, 12:15–15:15, Poster A
Finite-temperature density-functional theory of the Hubbard model — •Tobias Müller and Gustavo Pastor — Universität Kassel, Heinrich-Plett-Str. 40, 34132 Kassel
The finite temperature properties of the Hubbard model are investigated in the framework of lattice density-functional theory (LDFT). The single-particle density matrix γij with respect to the lattice sites is considered as the basic variable of the many-body problem. Following Mermin’s theorem the free energy F = E − TS = K + W −TS at temperature T is regarded as a functional of γ, where K[γ], W[γ] and S[γ] stand for the kinetic-energy, Coulomb-energy and entropy functionals, respectively. A finite-temperature extension of Levy’s constraint search approach is formulated. In this framework exact numerical results for W and S are obtained as a function of the nearest-neighbor γij and T for different system sizes at half-band filling. The properties of these functionals are discussed in some detail. On the basis of this analysis we propose a simple explicit approximation to W[γ] and S[γ] which is relevant to arbitrary lattices. The method is finally applied to one-dimensional systems and the accuracy of the derived equilibrium properties is discussed