Regensburg 2007 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 20: Poster session

MM 20.44: Poster

Tuesday, March 27, 2007, 14:45–18:00, Poster C

Wavefunction-based ab initio method for metals: applying the method of increments to magnesium — •Elena Voloshina and Beate Paulus — Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden, Germany

Calculations based upon the incremental scheme [1], that is an expansion of the total correlation energy in terms of one-body, two-body, and higher contributions, have been performed on a variety of solids [2]. Metals require special treatment because of two distinct features. Since the conduction bands are only partially filled, we cannot construct well localized orbitals from them. Furthermore, we must deal properly with charge screening which obviously is a correlation effect. One would expect that the metallic solid should be well described within DFT. Indeed, it is possible usually to select a DFT-functional that will yield good agreement of experimental and calculated properties. At the same time, it is well known, that the present DFT-based approaches are not amenable to systematic improvements. A starting point for the treatment of the many-body correlation effects in solids is a reliable HF SCF result for the infinite system. For magnesium HF model, ignoring the correlations, gives rather good agreement with experiment of one lattice parameter (c), but incorrect value for c/a ratio because of too high lattice parameter a. Application of the method of increments allow us not only to improve the HF values, but also explain the reason for these changes.

[1] H. Stoll, Phys. Rev. B 46, 6700 (1992).

[2] B. Paulus, Phys. Rep. 428, 1 (2006).