THE POLYMERIC STRUCTURE OF BECL2 FROM AN IONIC SIMULATION-MODEL

A polarizable ionic potential for BeCl2 is obtained from potentials de veloped previously to represent other group IIa chlorides, simply by s caling the cation radii. The BeCl2 potential reproduces the known stru cture of the isolated molecule and crystal and is used in simulations of the melt and molten mixtures with the 'network modifier' KCl. The s imulations show that the quasi-polymeric molecules, consisting of chai ns of edge-sharing BeCl4 tetrahedra, which are known in the crystal, p ersist as chains of finite length in the melt. The physical factors re sponsible for the emergence of such local structure for an ionic inter action model are discussed. The addition of the network modifier cause s the molecular chains to break down into a mixture of ionic species. The evolution of this process, as observed in the experimental Raman s pectra, is reproduced successfully by that of certain projected vibrat ional densities of states in the simulation.