Correlation analysis of chemical bonds (CACB) II: Quantum mechanical operators for classical chemical concepts

We apply correlation analysis of chemical bonds (CACB) to simple organic reaction paths. CACB, an operatorbased formalism for analyzing the electronic structure for molecule, clarifies how bond exchange processes relate to changes in covalent bond orders and bond interaction coefficients. For single bond-exchange processes, the bonds correlation typically is negative for interchanging bonds. For two bond-exchange processes, this coefficient can be either negative or slightly positive near zero, reflecting the nature of the bond exchange process. The simplest formalism can, sometimes, lead to unphysical values for the atomic valence and the bonds correlation coefficients. We analyzed the origin of this behavior and attributed it to the non-Hermitian property of the operator. We show how to avoid this problem by symmetrizing the operator through use of orthogonal atomic orbitals.