Some comments on the parameter choices for S.C.M.O. calculations on five membered heteroatomic ?-electron systems

Autor:	R. L. Flurry, J. J. Bell
Rok vydání:	1968
Předmět:	Matrix (mathematics) Fock matrix Chemistry Computational chemistry Yield (chemistry) Diagonal Heteroatom Charge density Charge (physics) Chiropractics Electron Physical and Theoretical Chemistry Molecular physics
Zdroj:	Theoretica Chimica Acta. 10:1-12
ISSN:	1432-2234 0040-5744
DOI:	10.1007/bf00529038
Popis:	It has been reported [1] that the usual semi-empirical S.C.M.O. treatments of heteroatomic π-electron systems yield unexpected dependencies of charge distribution on the βcore terms involving the heteroatoms. Other workers [2] have claimed that the most usual choices of parameters yield chemically unreasonable charge densities in furan and pyrrole. It is shown here that the first effect is related to the relative magnitudes of the diagonal elements of the Fock matrix and that the second depends very strongly on the nonnearest neighbor F matrix elements but can be overcome with certain parameter choices by the inclusion of non-nearest neighbor βcore terms in the calculations.
Databáze:	OpenAIRE
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