Statistical modeling of ion–molecule electrostatic capture

A statistical model is presented which enables rapid and accurate calculation of capture rate coefficients for the interaction of ions with neutrals possessing any combination of dipole, quadrupole, and isotropic or anisotropic induced-dipole moments. Rate coefficients at very low temperatures are calculated via the state-resolved statistical adiabatic channel model (SACM). At higher temperatures, a classical state-counting technique is utilized which may be derived either from microcanonical variational transition state theory or from the high-temperature limit of the quantized SACM approach. The predicted rate coefficients are generally accurate to within 10% in comparison with classical trajectory calculations.