The limiting ionic conductivity of Na+ and Cl- ions in aqueous solutions: Molecular dynamics simulation

Abstract

The molecular dynamics computer simulation technique was used to calculate the limiting ionic mobilities for Na+ and Cl- in TIP4P water. The velocity autocorrelation function and the memory kernel for the corresponding generalized Langevin equation were calculated for the mobile ion. The autocorrelation function of the force exerted on the stationary ion was also calculated and compared with the memory kernel. The two are in good agreement, especially at short times (≈0.1 ps). The diffusion coefficients obtained from Brownian motion theory (the stationary ion case) were also in good agreement with the ones obtained from mobile ion calculations. The major assumptions of the molecular theory of the limiting ionic mobility were tested and not confirmed by the simulation. © 1986 American Institute of Physics.