Diffusion between inequivalent sites

The use of localized functions is extended to obtain master equations for random walk processes among non equivalent sites, starting from a diffusional equation that includes a mean force potential. As a numerical application, the kinetic parameters are calculated for a collection of rotors in asymmetric double-minimum potentials, and for the trans-gauche isomerization of butane. These examples show that the transition rates and their Arrhenius behaviour are computed by projecting the diffusion operator onto a function set whose dimension is equal to the number of potential minima.