The LJ parameters for the sp 2 carbons and bonded hydrogens for benzene were transferrable to toluene and, as such, only the additional parameters for the methyl-group atoms were fit to the toluene reference data. Parameter sets yielding a molecular dispersion coefficient that deviated from the XDM value by more than a given threshold were discarded (see Table ). Molecular dynamics simulations were performed using the remaining parameter sets to calculate the density and enthalpy of vaporization of the liquid. Dispersion interactions were calculated using the LJ-PME method so that long-range dispersion interactions were included. The enthalpy of vaporization was calculated from the average potential energy the liquid simulation,