Theoretical studies on the cluster structure in the supercritical area

In supercritical fluid, solvent molecules form some characteristic clusters around solute molecules. The cluster structures were investigated by molecular dynamics simulations using supercritical carbon dioxide fluid containing a naphthalene molecule. Diffusion coefficient of the naphthalene molecule was confirmed to show a large fluctuation when trajectory of the solute was treated by a time scale of 100 ps (picosecond). On the basis of radial distribution function between the solute and solvents, we summarized that the fluctuation of the diffusion coefficient of the solute molecule had a relation to a fluctuation of the solvent fluid density. This investigation gave us an image how we considered the cluster structure in the supercritical area. (C) 1998 Elsevier Science B.V.