UHF-SCF-PM3 MO method was used to calculate the pyrolysis initial reaction mechanism for ε-hexanitrohexaazaisowurtzitane (CL-20). All transition states, activation energies and potential curves of four possible reaction paths were obtained. It was found that the homolysis of N—NO₂ bond in five-membered ring is the initial step. And great changes of atomic net charge happened near the transition state.

Key words: potential curve, pyrolysis mechanism, net charge, activation energy, ε-hexanitrohexaazaisowurtzitane