Intermolecular interactions of liquid dichloromethane and equilibrium properties of liquid-vapor and liquid-liquid interfaces: A molecular dynamics study

Extensive molecular dynamics simulations are carried out to study the molec ular interactions, liquid states, and liquid/vapor properties of dichlorome thane. The study is also extended to the equilibrium properties of the liqu id/liquid interface of water-dichloromethane. The intermolecular interactio ns among water, dichloromethane, and water-dichloromethane are described us ing our polarizable potential models. The equilibrium properties of liquid dichloromethane, including the radial distribution functions, the intermole cular structural factor, the self-diffusion coefficient, and the dielectric constant, are evaluated. The dielectric constant is computed using Ewald s ummation techniques and the computed result compared reasonably well with t he available experimental data. Properties such as surface tensions and den sity profiles of liquid/vapor dichloromethane are evaluated. We found that the computed surface tensions for several temperatures are in excellent agr eement with experimental data. The computed density profile of the liquid/l iquid interface of water-dichloromethane is averaged over 1 ns and we found the computed profile to be quite smooth and stable. The effect of polariza tion on the liquid/liquid interfacial equilibrium properties is evaluated b y computing the dipole moments of water and dichloromethane molecules as a function of the distance normal to the interface. We found that these value s deviated significantly from the simulations that are based on nonpolariza ble potential models. We attribute these observations to the changes in the electric fields around the water and dichloromethane molecules near the in terface. (C) 1999 American Institute of Physics. [S0021-9606(99)70220-5].