The mechanisms dealing with the thermal decomposition of 5-nitro-1- hydrogen-tetrazole are studied by density function theory. The geometries of the reactants, transition states, intermediates and products are optimized at the B3LYP/6-31(d) level. The corresponding vibrational frequencies are calculated to take account of the zero- point vibrational energy (ZPE) and to identify the transition structures. The single point calculations are obtained at the CCSD(T) /6-31G(d,p) level. Three possible reaction channels are shown, including direct ring rupture channels and proton transfer channel. The one of N(1)-N(2) bond-breaking ring rupture channel agrees with the result reported before. The one dealing with proton transfer shows a new feature of the titled compound's thermal decomposition. The other one of N(4)-C(5) bond-breaking ring rupture has the highest activation barrier of all the three channels and therefore it occurs less often than the former two.

Key words: NITRO COMPOUNDS, TETRAZOLE, THERMAL DECOMPOSITION, TRANSITION STATE THEORY, CONFIGURATION