Effect of the treatment of long-range forces on the dynamics of ions in aqueous solutions

The goal of the present work is to study the dependence of the limiting ionic mobility of such anions as fluoride, chloride, and bromide in water on the way the long-range forces are treated in the computer simulations. With this in mind we have performed molecular dynamics computer simulations where the long-range electrostatic forces were treated using: (a) simple truncation procedure, (b) energy switching procedure, (c) reaction field method, and (d) Ewald summation technique. Our analysis shows that the switching procedure with the short-range switching function introduces artifacts into the simulations. These artifacts are responsible for the faster decay and oscillations in the velocity autocorrelation function of the ions and therefore for the lower value of the diffusion coefficients.