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Recent years, in order to seek for ideal high energy materials (HEM) in an economical and efficient way, one urgently expects to predict the important properties of explosive inclusive of crystal structure, energetic property, mechanical property, and sensitivity. It has been understood from some experimental results that the safety and mechanical property of HEM have a close relationship with the intermolecular interaction in it. In examining nature of the interaction and molecule design of HEM, intermolecular forces, viz., dispersion, repulsion, induction, and electrostatic forces, have to be derived. The most theoretical means to obtain the forces is by the calculations based on the symmetry-adapted perturbation theory (SAPT). However, because the traditional SAPT method consumes a large amount of computational resources, it is very hard to extend it to HEM. This therefore becomes a theoretical puzzle of the HEM molecule design. The strong cooperative effect in the intermolecular interaction has a severe influence on the crystal structure and other important properties. In the case, only on the additive forces in carrying out the molecule and materials designs, must it be impossible to correctly predict properties of HEM. And in the hydrogen bonded high energy system, the non-additive effect may exhibit a strong or weak or anti cooperativity. One is expected to address the problems about the relationship of the cooperativiy with hydrogen bonding and its physical origin. On the other hand, DFT has been widely applied to the investigations of the HEM intermolecular interactions. However, with molecular size and its concomitant dispersion effect increasing, the appropriateness of DFT for the dispersion in the high energy systems must be evaluated. One must first disclose the basic terms in the DFT intermolecular interaction energy, otherwise, it is hard to utilize DFT to reliably predict the structures and properties of the systems.The work tries to address the above-mentioned theoretical and practical problemsencountered in the HEM molecule design. The main results and conclusions of the workare as follow:1. In terms of the traditional SAPT and utilizing the infinite filed, non-perturbative, coupled Hartree-Fock (CHF), and sum over all states (SOS) methods, we have computed the respective intermolecular forces—electrostatic, exchange repulsion, induction, and dispersion forces of nitramide dimer, the most simple model of the nitroamine high energy system, at different intermolecular separations (R). The calculations can provide high accurate theoretical data for the extension of the subsequent extension of a new SAPT(DFT) approach into HEM. On this basis, we have also examined in detail the different proportions of the respective forces in the intermolecular interactions and
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