  Propylene carbonate (PC) wets graphite with a contact angle of 31 deg at
ambient conditions. Molecular dynamics simulations agree with this contact
angle after 40% reduction of the strength of graphite-C atom Lennard-Jones
interactions with the solvent, relative to the models used initially. A
simulated nano-scale PC droplet on graphite displays a pronounced layering
tendency and an Aztex pyramid structure for the droplet. Extrapolation of the
computed tensions of PC liquid-vapor interface estimates the critical
temperature of PC accurately to about 3%. PC molecules lie flat on the PC
liquid-vapor surface, and tend to project the propyl carbon toward the vapor
phase. For close PC neighbors in liquid PC, an important packing motif stacks
carbonate planes with the outer oxygen of one molecule snuggled into the
positively charged propyl end of another molecule so that neighboring molecule
dipole moments are approximately antiparallel. The calculated thermal expansion
coefficient and the dielectric constants for liquid PC agree well with
experiment. The distribution of PC molecule binding energies is closely
Gaussian. Evaluation of the density of the coexisting vapor then permits
estimation of the packing contribution to the PC chemical potential, and that
contribution is about 2/3rds of the magnitude of the contributions due to
attractive interactions, with opposite sign.
