Non-nuclear attractors on Si-Si bond in quantum-chemical modeling as basis set inadequacy

Electron density distribution in disilane molecule computed using several methods (Hartree-Fock, Moller-Plesset perturbation theory, density functional theory, configuration interaction) and basis sets (correlation consistent as well as Hartree-Fock-parameterized) is studied in the frame of the topological analysis. It is shown that nonnuclear attractors (pseudo-atoms) on Si-Si bond are caused by inadequacy of the basis set only. Accounting for electron correlation cannot in general fully correct the picture. It is noted that considerable success of the method B3LYP/6-31G(d,p) when applied to silicon surface and clusters is to be explained by an occasional reproducing of Si-Si stretching mode value, whenever the method tends to give an incorrect Si-Si bond electron density distribution. (C) 2003 Elsevier Science B.V. All rights reserved.