Collect. Czech. Chem. Commun. 1980, 45, 2463-2473

Topological analysis of energy hypersurface

Jiří Pancíř

The J. Heyrovský Institute of Physical Chemistry and Electrochemistry, Czechoslovak Academy of Sciences, 121 38 Prague 2


Topological approximations discussed in the preceeding paper are used for construction of topological energy hypersurfaces of chemical reactions on two levels of a sophistication. A method of a linear change of off diagonal matrix elements reproduces adequately Woodward-Hoffmann rules but it provides only qualitative information about energetical relations. A physically more rigorous hypothesis where the reaction driving force is a function of hybridization changes at reaction sites provides energy hypersurfaces which are correct from a quantitative viewpoint. The method suggested treats the total energy as a function of abstract reaction angles which reflect topological changes accompanying the reaction course. A reaction mechanisms analysis leads then to the analysis of topological energy hypersurfaces which can be treated similarly to that of conventional geometrical hypersurfaces. Formulas for atomic integrals necessary in the construction of Hartree-Fock and CI matrices are derived in the basis of reaction angles mentioned and approximations leading to the semiempirical type of a calculation are discussed.