Molecular dynamics simulations of a potassium ion and an iodide ion in liquid ammonia

The systems consisting of one K+ with 215 ammonia and one I- with 215 ammonia molecules have been investigated by molecular dynamics simulations at an average temperature of 240 K, using a flexible ammonia model. K+-ammonia and I--ammonia pair potentials were constructed from ab initio calculations with basis set superposition error (BSSE) correction. Eventual non-additivity of the K+-ammonia potential has been also examined. Structural properties of the solutions were investigated through radial distribution functions (RDFs) and their running integration numbers, leading to coordination numbers of 8.7 and 12-15 for K+ and I-, respectively. Velocity autocorrelation functions and their Fourier transforms, describing the dynamical properties of the solutions, are in good agreement with available theoretical and experimental data. (C) 1997 Elsevier Science B.V.