Molecular mechanics (MM) method with Compass and Dreiding force fields is used to predict molecular packing for DPO among the 7 most possible space groups (P2(1)/c, P-1, P2(1)2(1)2(1), P2(1), Pbca, C2/c, and Pna2(1)), respectively. Then, periodic band calculations are performed on the predicted crystals using the DFF-GGA-PBE method. Obtained density of state (DOS) shows that C-O, C-NO2 and N-N bonds are possibly the trigger bond during thermolysis. Band gap (Delta E-g) equals 1.33 eV, which shows DPO with higher sensitivity. Periodic calculation results are consistent well with that drawn from bond dissociation energy calculations on gas molecule. (C) 2009 Elsevier B.V. All rights reserved.