Molecular dynamics simulations of simple dipolar liquids in spherical cavity: Effects of confinement on structural, dielectric, and dynamical properties

The equilibrium and dynamical properties of Stockmayer liquids confined in a spherical cavity are investigated by means of molecular dynamics simulations. The simulations are carried out at varying density and cavity size. Various equilibrium and time dependent quantities such as the spatial and orientational density profiles, dielectric constants, average energies, pressures, components of translational diffusion tensors parallel and perpendicular to the cavity surface, rotational diffusion coefficients and several time correlation functions are calculated and the effects of confinement on the above properties are discussed. The density profiles are found to be highly inhomogeneous near the cavity wall, and the dielectric constant of the liquids in cavity is found to be significantly smaller than that of the bulk phases. The diffusion along the surface normal and also the dipolar orientational relaxation of solvent molecules in cavity are found to slow down because of confinement. The dynamics of solvation of a newly created charge distribution in the cavity is also studied and the results are compared with the dynamics of solvation in bulk solvent. The solvation in the cavity is found to occur at a much slower rate.