Ionic dynamics in the glass-forming liquid ${\mathrm{Ca}}_{0.4}{\mathrm{K}}_{0.6}{(\mathrm{N}\mathrm{O}}_3{)}_{1.4}:$ A molecular dynamics study with a polarizable model

The microscopic dynamics of the fragile glass-forming liquid ${\mathrm{Ca}}_{0.4}{\mathrm{K}}_{0.6}{(\mathrm{N}\mathrm{O}}_3{)}_{1.4}$ is investigated by molecular dynamics simulation with a polarizable model. Polarization effects are included within a fluctuating partial charges approach for the nitrate ion. Single-particle time-correlation functions are compared with the ones obtained by the nonpolarizable model counterpart. It is argued that the increased ionic mobility due to polarization effects corrects the stiff dynamics of the nonpolarizable model. Among the collective functions that have been calculated with the polarizable model, special attention is paid to the density fluctuations in wave vectors around the first sharp diffraction peak of the static structure factor. In line with recent neutron-scattering experiments, an intermediate-range-order dynamics has been observed in the simulated system.