SIZE DEPENDENCE OF SOLVATION STRUCTURE AND DYNAMICS OF IONS IN LIQUID N-METHYLACETAMIDE: A MOLECULAR DYNAMICS SIMULATION STUDY

The solvation structure and dynamics of alkali metal (Li+, Na+, K+, Rb+, Cs+) and halide (F-, Cl-, Br-, I-) ions in liquid N-methylacetamide (NMA) are calculated at two different temperatures T = 313 K and 453 K, by using classical molecular dynamics simulations. We have also considered NH4+ and some larger cations such as I+, Me4N+, and Et4N+ in this study to investigate the size dependence solvation structure and dynamics of ions in liquid NMA. With the increase of ion size, the self-diffusion coefficients of cations are found to increase and the maximum is observed at Me4N+, whereas for halide ions the increase of diffusion coefficient with ion size continues up to I- and no maximum is observed. However, the relative increase of the diffusion coefficients of larger ion compared to those of Li+ and F- are found to be significantly higher at low temperature. Results are very good in agreement with experimental observation.