The polarizabilities of CH and CC bonds

Abstract

A variant of uncoupled Hartree–Fock perturbation theory is described which uses as zero‐order function a Hartree–Fock wavefunction built up from localized orbitals. The second‐order energy has the form of a sum of contributions from the individual orbitals which, since the orbitals are typically localized along bonds, can be interpreted as the sum of bond contributions. A variational procedure for computing these bond contributions is derived and applied to finding the components of the electric polarizability tensor for the CH and CC bonds in the molecules methane, ethane, ethylene, and acetylene.