Nowe funkcjonały gęstości elektronowej do modelowania układów związanych niekowalencyjnie

The main part of this work deals with the problem of constructing density-functional methods within the realm of hybrid semilocal approximations, that is, within the set of practical electronic-structure methods that can be applied to real-world molecular systems. In a series of works, the author demonstrates the merits of various building blocks of approximate functionals: the kinetic energy dependence of the exchange-correlation functional, dispersion correction, and long-range correction to the DFT exchange energy. The prototype method which includes these elements is the MCS functional; this method is, however, restricted to the description of noncovalent systems. The final and most complete method devised by the author is a scheme for converting an existing exchange functional into its range-separated hybrid variant. The approach is based on the exchange hole of the Becke-Roussel type, which has the exact second-order expansion in the interelectron distance. The LC-PBETPSS functional, which is constructed by applying this scheme, combines the range-separated PBE exchange lifted to the meta-GGA rung and the TPSS correlation. Numerical tests show remarkably robust performance of the method for noncovalent interaction energies, barrier heights, main-group thermochemistry, and excitation energies

Density Functional Theory Approach to Noncovalent Interactions via Interacting Monomer Densities

A recently proposed "DFT+dispersion" treatment (Rajchel et al., Phys. Rev. Lett., 2010, 104, 163001) is described in detail and illustrated by more examples. The formalism derives the dispersion-free density functional theory (DFT) interaction energy and combines it with the dispersion energy from separate DFT calculations. It consists in the self-consistent polarization of DFT monomers restrained by the exclusion principle via the Pauli blockade technique. Within the monomers a complete exchange-correlation potential should be used, but between them only the exact exchange operates. The applications to wide range of molecular complexes from rare-gas dimers to H-bonds to pi-electron interactions show good agreement with benchmark values.Comment: 9 pages, 5 figures, 2 tables, REVTeX