Construction of a Potential Energy Surface Based on a Diabatic Model for Proton Transfer in Molecular Pairs

Abstract

We propose a simple construction method of the potential energy surface based on diabatic model for proton transfer in molecular pairs. Assuming two-state valence bond electronic wave functions as a diabatic basis, the diagonal and non-diagonal matrix elements in diabatic potential of water, ammonia, and imidazole pairs were obtained. The validity of the construction procedure was confirmed by comparing two adiabatic potentials: one was transformed from the obtained diabatic potential and another was calculated by DFT calculation. Diabatic potentials were also obtained using fewer reference points than conventional methods at various intermolecular distances. Finally, we discuss the resulting diabatic potential and non-diagonal elements in detail.