Molecular dynamics method has been used to study NaCl-NaBr molten salt mixture, as one of the simplest examples of common cation molten salt systems. It has been found that some Cl- and Na+ ions in NaCl-NaBr mixture tend to form denser ionic clusters, while the Br- ions distribute in the spaces between the Na Cl clusters. The number of ions with No ≤3 increases in the mixing process between NaCl and NaBr melts. The internal energy data of NaCl, NaBr and NaCl-NaBr (1:1) melts estimated by the molecular dynamics are in agreement with the "experimental data" estimated by Born-Haber cycle. These internal energy data indicate that the mixing process between NaCl and NaBr melts is slightly endothermic. This is chiefly due to the increase of the short-range repulsion energy between Na+ ions and halide anions.
