Development of a wavefunction-based ab-initio method for metals applying the method of increments

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The purpose of this proposal is the application of wavefunction-based quantum chemical correlation methods to metals via the incremental scheme. The correlation energy of the solid is expanded in terms of localized orbital groups and increments of these groups. The first application was made for solid mercury, where we achieved a very good agreement with experimental ground-state properties. In the last two years we have extended the method to magnesium, zinc and cadmium, where the metallic character is more pronounced than in mercury. We have developed and tested different approaches for the embedding and the localized orbitals used for the incremental scheme. The calculated ground-state properties agree very well with the experimental values. In the next period of the priority program we want to extend the method of increments to the other group IIa metals and to open-shell metals like lithium and gold. In both cases it is expected that single-reference correlation methods as used up to now will fail due to quasi-degenerate bands at the Fermi level. For that reason we want to develop a multi-reference incremental scheme for three-dimensional solids.