About the conference on the Theory of the Structure and Spectra of Complex Systems

K. A. Timiryazev Agricultural Academy. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 1, p. 3, January–February, 1993.     

Comparison of various approximations for the AB initio calculation of molecular electronic orbitals

Theoretical and Experimental Chemistry -     

To the question on radiationless transitions in electronically excited zones of molecular crystals

A model is proposed describing the dynamics of radiationless transitions in the energy zones corresponding to excited electronic states in molecular crystals. In this model, the migration effect is explicitly reflected, which initially appears under pulse excitation of the systems with a periodical structure of a density distribution of states in separate parts of molecular crystals.     

Σ-Factorization method: A new development of molecular-orbital theories based on one-centre approximation of atomic and molecular densities

A new approach to one-centre approximation methods initiated by Mulliken and Ruedenberg in their earlier works has been developed in this paper. Despite the similarity of underlying ideas, the proposal to factorize thes-function product instead of the total density factorization along with a new technical background of the method provide more flexible and practical scheme since large orbital quantum numbers do present no longer the crucial point for extending the approach for compounds with heavy atoms. Both minimal and extended schemes are equally within the scope of the method. The technical links with the nuclear shell model formalism are discussed briefly.