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A new tool for the rapid estimation of charge distribution
Author(s) -
Houser John J.,
Klopman Gilles
Publication year - 1988
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.540090811
Subject(s) - cndo/2 , diagonal , steric effects , parameterized complexity , charge (physics) , computational chemistry , chemistry , matrix (chemical analysis) , hückel method , molecule , point (geometry) , charge density , physics , mathematics , quantum mechanics , molecular orbital , stereochemistry , organic chemistry , geometry , algorithm , chromatography
A method has been developed which uses a rapid connectivity‐based calculation to give a reasonable approximation of CNDO σ and π charges for most carbons in saturated and unsaturated hydrocarbons. In this calculation an appropriately parameterized Del Re method is used to calculate the σ charges, and if the molecule is unsaturated, these charges are used to modify the diagonal elements in a Hückel matrix, reducing the normally exaggerated π charges. The CNDO charges are obtained from “single point” calculations, using optimized geometries derived from molecular mechanics. The Del Re/Hückel method is most reliable where steric and hyperconjugative effects are absent.