STATIC STRUCTURE AND IONIC TRANSPORT IN MOLTEN AGBR AND AGCL

The static structure of molten AgBr and AgCl have been calculated usin g the hypernetted chain theory of liquids (HNC) and molecular dynamics simulations (MD) with effective potentials based on the functional fo rm originally proposed by Vashishta and Rahman [Phys. Rev. Lett. 40, 1 337 (1978)] to study alpha-AgI. The HNC anti MD are in good agreement among themselves as well as in good qualitative agreement with experim ent. MD simulations have been also used to calculate the time correlat ion functions and ionic transport properties of these melts. The resul ts for the velocity autocorrelation functions suggest, in both cases, a mechanism for diffusion akin to that we suggested for molten AgI and CuX (X = Cl, Br, I) [J. Phys. Condens. Matter 2, 6643 (1990)] even th ough the cations velocity autocorrelation function is no longer purely diffusive. The results for the diffusion coefficients resemble the ty pe of behavior found in superionic melts, as if the transition to a su perionic state is finally realized in AgCl and AgBr on melting. The re sults for the specific ionic conductivities are in good agreement with experiment if it is assumed that the ions, in their transport, carry with them their full complement of electrons. (C) 1997 American Instit ute of Physics.