Modelling of structure and dynamics of molten NaF using first principles molecular dynamics

Some aspects of the microscopic structure and dynamics in molten NaF are presented by first principles MD simulations. From distribution plots of NaF inter-ionic distances, F-Na-F angles and local coordination numbers of the melt structure have been studied. The analysis of coordination numbers shows that most of the Na or F are surrounded by four to five ions of opposite polarity. This is different from their solid state form, where octahedral environment is expected for each ion. The dynamical properties of molten NaF are investigated through the self-intermediate scattering function I(Q,t). The calculated I(Q,t) compares well with the experimental one obtained through Fourier transformation. The power spectrum of the velocity autocorrelation function from the MD simulation allows to obtain partial density of states of molten NaF, which links diffusive motions with the vibrational density of states. The short, medium and long time motion of molten NaF is discussed on the basis of these calculations.Some aspects of the microscopic structure and dynamics in molten NaF are presented by first principles MD simulations. From distribution plots of NaF inter-ionic distances, F-Na-F angles and local coordination numbers of the melt structure have been studied. The analysis of coordination numbers shows that most of the Na or F are surrounded by four to five ions of opposite polarity. This is different from their solid state form, where octahedral environment is expected for each ion. The dynamical properties of molten NaF are investigated through the self-intermediate scattering function I(Q,t). The calculated I(Q,t) compares well with the experimental one obtained through Fourier transformation. The power spectrum of the velocity autocorrelation function from the MD simulation allows to obtain partial density of states of molten NaF, which links diffusive motions with the vibrational density of states. The short, medium and long time motion of molten NaF is discussed on the basis of these calculations.