Abstract: Three optimized geometries of N-methyl nitroamine dimers were obtained with %ab initio% calculation at HF/6-31G^* level. All the binding energies of the dimers, evaluated as the sum of the HFinteraction energy and MPcorrelation interaction energy, are corrected for the basis set superposition errors(BSSE) and for zero point energies(E_ZP). The corrected combining energy of the most stable dimer is -18.81 kJ·mol^-1. The internal rotation of methyl has an influence on the intermolecular interaction. The change of the Gibbs free energy proceeding from monomer to the most stable dimer is 10.02 kJ·mol^-1 at 298.2 K. The effect of temperature on the process has also been discussed.

Key words: N-methyl nitroamine, Intermolecualr interaction, Ab initio, Thermodynamic properties