The energy bands, electronic stmctures and relationship between structures and properties of the ciystalline a-lead azide were investigated with periodic ab initio method. The atomic overlaps and electron densities show that there exists some covalency between the metal and the azide group. The ciystal lattice energy, corrected for the basis set supeiposition errors, is -2187.35 kj'mol"1. This value is in good agreement with that estimated by Gray's approximate method. Atomic charge on Pb~(2+) is actually ca. 1.27 a. u. , indicating that some electrons have been transferred from azide anion to lead cation in the a-Pb(N_3)_2 crystal. The frontier bands are uneven and crossed. The frontier occupied ciystal orbitals mainly consist of the atomic orbitals of the terminal nitrogen atoms of azide, while the frontier virtual crystal orbitals consist of those of lead, which facilitates the electron leap from the terminal nitrogen to lead. Consequently, a- Pb(N_3)_2 is expected to be sensitive explosives, according to the "principle of the easiest transition". It is thus suitable to be used as an initiating high explosive.

Key words: Pb(N_3)2, CRYSTALS, AB INITIO CALCULATION, BAND STRUCTURES, ELECTRONIC STRUCTURE