MONTE-CARLO SIMULATIONS OF A MAGNESIUM-ION IN LIQUID-AMMONIA

An infinitely dilute solution of Mg(II) in ammonia solution is studied by Monte Carlo simulations for two temperatures, using a newly developed Mg(II)-ammonia potential function based on ab initio calculations with a DZP basis set. The structure of the solution is described by radial and angular distribution functions (RDF). The first shell coordination number of 8 remains constant upon increasing the temperature from 235 to 277 K. A small peak is observed in the Mg(II)-nitrogen RDF between the first and the second solvation sphere, consisting of two ammonia molecules. The strong influence of the magnesium ion on the orientation of the ammonia molecules and the structure of the solvation shell are discussed. The results are compared with those of previous simulations for lithium and sodium ions in ammonia, water and in aqueous ammonia.