Cation dependence of the ionic dynamics in computer simulated molten nitrates

In order to study the cation dependence of the ionic dynamics in molten nitrates, molecular dynamics simulations including vibrational degrees of freedom were carried out for molten LiNO3, NaNO3, and RbNO3. Coulomb pair potential with Born‐type repulsion was adopted for the interionic interaction. The simulated diffusion coefficient was smaller for a larger cation, and that of nitrate ions did not change with changing cation species. The mean squared charge displacements showed that the static conductivity decreased considerably as the cation size increased from Li+ to Rb+. The simulated orientational correlation function of nitrate ions decayed more quickly as the cation size increased. Far infrared absorption spectrum simulated from the time evolution of the dipole moment (or the current) of the system showed that the peak shifted to the low energy side and the intensity decreased as the cation size increased. Results of the simulation were compared with the experimental diffusion constants, static and ...