Bond Calculations and Their Applications to Medium-Sized Conjugated Hydrocarbons

Valence Bond Calculations and Their Applications to Medium-sized Conjugated Hydrocarbons 

Department of Chemistry, Nanjing University, Nanjing, 210093, P. R. China 1. INTRODUCTION 

The origin of the VB model the Heitler-London treatment of the hydrogen molecule 

Here h i), z =l or 2, stands for the core Hamiltonian for electron i moving in the field of nuclei a and b separated by distance R, and g(l,2) is the repulsion potential between two electrons away from each other by distance rl2. 

According to Heitler and London [1], the electronic states of the hydrogen molecule can be formed by distributing the two electrons between the atomic orbitals (AOs), Ls and 1 sb (abbreviated by a and b), on the two hydrogen atoms. The singlet wave function characterized by quantum numbers S=0 and M=0 (M denotes the z-component of total spin S) can be described using the form 

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Jiang, Y. Li, S. Valence Bond Calculations and Their Applications to Medium-sized Conjugated Hydrocarbons. In Valence Bond Theory, Cooper, D. L., Ed. Elsevier Amsterdam, 2002 Chapter 18, pp 565-602. 

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