Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 84: Joint Focussed Session: Theory and Computation of Electronic Structure: New Frontiers VII

HL 84.6: Talk

Thursday, March 17, 2011, 18:45–19:00, TRE Phy

Finite temperature reduced density matrix functional theory (FT-RDMFT) A novel approach to the description of quantum systems in thermal equilibrium. — •Tim Baldsiefen and E.K.U. Gross — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany

Despite the big success of DFT for the description of groundstate properties of quantum mechanical systems, the finite temperature extension FT-DFT showed only little success in a restricted field of research. We develop the theoretical foundation for an alternative description of equilibrium properties, by employing the one-reduced density matrix (1RDM) rather than the density as central variable. The zero-temperature version of this theory proved to be quite successful in the last years, allowing for the description of groundstate properties of a wide class of systems (e.g. small molecules [1] and solids [2]). This sparks the hope, that a description of finite temperature ensembles by means of the 1RDM will succeed on fields of research formerly inaccessible by FT-DFT.

In this framework of FT-RDMFT we are able to employ methods from many body perturbation theory to develop approximate free-energy functionals. An application to the groundstate of the electron gas shows, that FT-RDMFT is able to significantly improve the groundstate energy compared to a strictly perturbative treatment.

[1] N. N. Lathiotakis et al., Phys. Rev. A, 79, 040501 (2009)

[2] S. Sharma et al., Phys. Rev. B 78, 201103(R) (2008)