Coulomb liquids under electric field – application of a new computer simulation method

Abstract

Basics and some applications of a new method for computation of Coulomb forces in Monte Carlo or molecular dynamics simulation of highly non-ideal disordered systems like strongly coupled plasma and hightemperature ionic liquids is discussed. This method, based on angular averaging of Ewald sums over all orientations of the reciprocal lattice vector, eliminates periodicity artifacts imposed by conventional Ewald scheme under conditions of computer simulation and provides much faster computation of electrostatic interactions in simulation of disordered condensed systems. Application of this approach to study of solvation effect on transport properties of ionic liquids under strong electric field is discussed. Diffusion coefficients and external mobilities of ions are determined and analyzed in relationship to structure characteristics of the melt. External ionic mobilities of heavy actinide ions in their different oxidation states in lithium chloride-potassium chloride eutectic melt at high temperature are determined using ionic model and Fumi-Tosi potentials. Negative values of external mobilities of multiple charged actinide ions are found. In order to explain this effect, radial distribution functions, coordination numbers, and dynamic structure characteristics of solvated ions are determined and analyzed. Concentration dependency of the apparent charges of Li⁽⁺⁾, K⁽⁺⁾, and Cl⁽⁻⁾ was studied at constant density in the whole range of Li concentrations from pure LiCl to dilute solution of LiCl in KCl. It was found that the apparent charge of Li⁽⁺⁾ ion at low concentrations also becomes negative. The explanation for this effect based on structure and stability of solvation shells discussed.