Two fully optimized geometries of NH~3+NH~2NO~2 are obtained using the ab initio method at the HF/6-31G^* level, and the accurate intermolecular interaction energy is calculated using the MP4 electron correlation correction and the basis set superposition error correction by the Boys-Bernardi "counterpoise" protocol. In addition, the PM3 method is employed to study the intermolecular interactions of TATB (1, 3, 5-triamino-2, 4, 6-trinitrobenzene) with HMX (ocotogen) and RDX (hexogen). The intermolecular interaction energies with approximation of electron correlation correction by the dispersion energy are given. The computed results indicate that the greatest binding energy of NH~3+NH~2NO~2 is -38.32kJ/mol. The intermolecular interactions can strengthen the N-NO~2 bond. The binding energies of TATB with HMX or RDX are much larger than those between graphite and HMX or RDX. Therefore TATB can wet and desensitize HMX (or RDX) better than graphite.

Key words: AB INITIO CALCULATION, AMMONIA, HMX, BINDING ENERGY, MOLECULAR ORBITAL METHOD, COMPOSITE EXPOLOSIVES