| Although density functional theory stays as the most used method in the field of solid-state physics and computational material science, there is no clear way to systematically improve the result upon the present density functionals. This yields preferences to the wavefunction-based techniques, like the Mĝller-Plesset perturbation theory or the coupled-cluster. A possibility to apply these highly-accurate quantum-chemical methods to extended systems is the use of the so-called local correlation schemes, which exploit the local character of the electronic correlations. One method of this type, the method of increments, combines Hartree-Fock calculations for solids with correlation calculations for its finite embedded clusters, and the total correlation energy per unit cell is written as a cumulant expansion in terms of contributions from localized orbital groups of increasing size. Since its development, the method of increments has been applied to a large variety of materials [2-4]. The obtained ground-state properties are shown to agree well with the experimental data. In my talk, I will present the method of increments in its general formulation and its extension for studying low-dimensional systems, like surfaces and adsorption on surfaces. [1] H. Stoll, Phas. Rev. B 46, 6700 (1992). [2] B. Paulus, Phys. Rep. 428, 1 (2006). [3] E. Voloshina and B. Paulus, Chemical Modelling 6, 162 (2009). [4] C. Müller and B. Paulus, Phys. Chem. Chem. Phys. (accepted). |
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