Molecular dynamics simulation of molten sodium chlorate

Abstract

Molecular dynamics (MD) simulation has been used in a detailed investigation of structure and dynamics of molten sodium chlorate, NaClO3. Results obtained with nonpolarizable and polarizable models are compared, the latter being implemented by using a fluctuating charges approach for the anions. The partial charges of the nonpolarizable model and the parameters of the polarizable model were obtained by ab initio calculations of a single ClO3− anion. The calculated static structure factor of molten NaClO3 is in good agreement with recent neutron scattering results. A detailed picture of the distribution of cations-around the anions is provided. Proper to the rather large dipole moment of the ClO3− anion, short-range dipole ordering between pair of anions is discernible in the MD simulations. The equilibrium structure of molten NaClO3 is not too affected by including polarization effects on the anions, but significant polarization effects are observed in the dynamics of the simulated system. The ionic diffusion coefficients increase by including polarization effects, so that the polarizable model gives higher conductivity and lower viscosity than the nonpolarizable model.