Molecular dynamics (MD) simulations have been performed for several pure alkali nitrate melts. Special attention was paid to the examination o f the interaction potential: macroscopic quantities like pressure were calculated and compared with real values. To improve the results the commonly used potential for alkali nitrates (Coulomb pair potential and Born-type repulsion) has been extended by a short-range-attraction term to meet the real behaviour o f the liquid.With these improved potentials, simulations of pure L iN 0 3, N a N 0 3, K N 0 3, and R b N 0 3 have been performed with special regard to the influence of size and mass o f the cations on the transport effects to show analogies to isotope effects. The calculated self diffusion coefficients (SDC) have been compared to results obtained with the NMR spin echo method.