Electronic Density Changes for Non-Equilibrium Molecular Geometries: A Charge – Charge Transfer – Dipolar Polarization Model

Atomic charges and atomic dipole moments are sufficient and necessary to accurately model molecular dipole moment derivatives and infrared intensities, providing useful information about electronic densities of non-equilibrium configurations. Charge transfer – counter-polarization effects are important for most vibrational intensities. Models contemplating only atomic point charges may calculate the correct band intensity for most normal coordinate types but fail to reproduce the intensity of out-of-plane distortions. The Charge – Charge Transfer – Dipolar Polarization (CCTDP) model permits atomic partitioning of infrared intensities as well as understanding GAPT charges and infrared intensifications experimentally related to hydrogen bond stability. The model successfully describes the electron transfer used to explain the SN2 transition state and intrinsic reaction path indicating its potential usefulness for understanding chemical reactions.