A new ab initio based model potential for methane

We present a model potential for methane based on BSSE corrected MP3 level interaction energies of 132 methane dimers using the aug(df,pd)-6-311G** basis set (6-311G** basis set augmented with diffuse d and f functions on carbon atoms and diffuse p and d functions on hydrogen atoms). The density, heat of evaporation and self-diffusion coefficient of liquid methane obtained by an MD simulation using the model potential reproduced the experimental values considerably better than the previous model potential based on MP3/6-311G(3d,3p) level interaction energies.