Molecular Dynamics Study of a Lithium Ion in Ammonia

Abstract

Abstract A Molecular Dynamics simulation of a solution of one Li+ in 215 NH3 molecules has been performed at an average temperature of 235 K. A newly developed flexible model for NH3 is employed and the Li +−NH3 interactions are derived from ab initio calculations. The structure of the solution is described by radial distribution functions and the orientation of the molecules. A solvation number of six is found for Li+ and a strong preference of the solvation shell molecules exists for an orientation where the Li + −N vector and the dipole moment direction of NH3 are parallel. The self-diffusion coefficient, the hindered translational motions and librations are calculated separately for the ammonia molecules in the solvation shell and in the bulk. The effect of Li + on intramolecular geometry and vibrations is reported.