Prediction of crystalline densities of polynitro arenes for estimation of their detonation performance based on quantum chemistry

Thirty nitro aromatic compounds are studied using the density functional theory B3LYP method with six basis sets (3-21G, 6-31G, 6-31G∗, 6-31G∗∗, 6-311G∗ and 6-31+G∗∗) and semiempirical PM3 method. Based on the geometries optimized at various theoretical levels, the molecular volumes and densities are calculated. Compared with the experimental results, the densities estimated by the PM3 and B3LYP/3-21G methods are all systematically larger, and that obtained with the other five basis sets are better and quite accurate. Considering that a larger basis set demands more computer resource, B3LYP/6-31G or 6-31G∗ is recommended for rapid and reliable prediction of crystalline densities. The effect of various groups on the densities is discussed. Based on the theoretical densities, it is possible to estimate the detonation properties, which will be helpful to rapidly and effectively design and screen promising candidates of high energy density materials (HEDMs).