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Simplified SCF calculations for σ‐bonded systems. II. The interhalogens
Author(s) -
Pohl Herbert A.,
Raff L. M.
Publication year - 1967
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560010505
Subject(s) - helmholtz free energy , series (stratigraphy) , chemistry , work (physics) , yield (engineering) , diagonal , molecule , computational chemistry , electron , thermodynamics , atomic physics , quantum mechanics , physics , mathematics , paleontology , geometry , organic chemistry , biology
A series of simplified LCAO MO SCF calculations has been carried out on the ten possible interhalogen molecules. In the model only the bonding electrons are considered explicitly. The bonded electron pair is described by a single Slater determinant and all integrals are evaluated by unadjusted, semiempirical techniques. Equilibrium separations, binding energies, and potential curves are obtained for each molecule, and the effect of the Wolfsberg–Helmholtz parameter in the off‐diagonal term is studied in detail. Without empirical adjustment, calculated electronic energies are accurate to about 2% while the bonding energies are too low by about 1 eV. Equilibrium distances are too small. The observed trends of these properties, however, are in satisfactory agreement with experiment. If desired, a single empirical adjustment of the Wolfsberg–Helmholtz parameter, K , suffices to bring the calculated binding energies of the entire series into good agreement with experiment. Previously suggested empirical forms for K yield poor results here and alternate proposals concerning the best procedure for determining, a priori , the best values for this parameter are made. In general it is concluded that the approximations utilized in this work are compatible and well‐suited for the description of σ‐bonded systems.