Collision rate constants for polarizable ions

Langevin described a model for the interaction between an ion and a neutral nearly a century ago and since then, many modifications have been introduced to adjust for specific circumstances. This work discusses the induced dipole-induced dipole interaction between an ion and a neutral without a permanent dipole and introduces an anisotropic adjustment. A point polarizable ion model (PPI) and an orientation dependent polarizable ion model (ODPI) are discussed and applied to systems where the ion is highly polarizable and the neutral is only weakly polarizable. Significant deviations from classical Langevin rate constants and significant differences between PPI and ODPI are observed.