On combining quantum chemistry and molecular mechanics. The potential energy surface of complexes of transition metals exemplified by spin transition in cis-[Fe(bipy)(2)(CNS)(2)]статья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:A new approach to calculating potential energy surfaces (PEP) of various spin states of transition-metal complexes is suggested. The approach is based on description of the electronic structure of a complex within the method of effective crystalline field (ECF) ire which the wave function is written as an anti-symmetrized product of the wave function of d-electrons calculated in the approximation of configurational interaction and the function of ligand electrons determined in the self-consistent field approximation. Within the ECF method an expression for the total energy of a molecule written in the form of a sum of the effective energy of d-electrons and ligands approximated by the molecular mechanics method (MM) is derived. The suggested approach is used to construct PES sections of various spin states of cis-Fe(bipy)(2)(NCS)(2) molecules along the straight line that connects the points pertaining to spin isomers in the configuration space. The MM parameters evaluated for iron atoms enable the total-energy terms to be reproduced in such a manner that they tit the available experimental characteristics of spin transitions.