Abstract: The geometries of DATB( 1,3-diamino-2,4 ,6-trinitrobenzene) and TATB( 1,3,5-tri-amino-2,4,6-trinitrobenzene) have been optimized by M1NDO/3 method. It is found that the total energy of the molecule is rather low at the plane configuration. It is also found that the orbitals between the amino-Nand its adjacent nitro-Nas well as the amino-Nand its adjacent nitro-Non the ring are rather close and matched in symmetry and have high orbital interaction through space, which are evidently seen from the computed results of the atomic bond index. The electronic spectra of DATBhave been computed by using INDO/2-CImethod, and the results are well conformed with the experimental facts. For instance, the transition from 'A' (ground state" ) to 'A' (the 7th exciled state) corresponds to the computed spectrum line(2.48×10⁴cm^-1) which is close to the experimental value (2.43×10⁴cm^-1). From a similar computation, we may predict that the major spectrum line of TATBwill be 2.75, 2.77, 3.28 and 3.32×10⁴cm^-1.

Key words: Electronic spectrum, Geometry, Stability