Intermolecular interaction potentials of the methane dimer from the local density approximation

The intermolecular interaction potentials of methane (CH4) dimer are calculated within the density functional theory in the local density approximation (LDA). It is found that the calculated potentials have minima when the intermolecular distance of CH4 dimer is about 7.0 a.u., which is in good agreement with the experiment. The depth of the potential is 0.017 eV. The results obtained by our LDA calculations seem to agree well with those obtained by MP2, MP3, and CCSD from the Moller-Plesset and coupled cluster methods by Tsuzuki and with the experimental data.