Periodic DFT study of adsorption of nitroamine molecule on α-Al2O3(0 0 1) surface

The adsorption of NH2NO2 molecule on the Al2O3(0 0 1) surface were investigated by the generalized gradient approximation (GGA) of density functional theory (DFT). The calculations employ a supercell model represented with 2 × 2 of periodic boundary conditions. The strong attractive forces between NH2NO2 molecule and Al2O3 induce obvious change of the NH2NO2 and Al2O3 structure. Although the NH2NO2 molecule does not decompose, Al-O bonds partially decompose and some O-O bonds form, whose bond lengths are intervenient between O=O double bond length and O-O single bond length. The largest adsorption energy is -453.8 kcal mol-1. By the adsorption energy and the change with structure of NH2NO2 and Al2O3, it can be concluded that aluminized explosive of NH2NO2 keeps high reactivity even if the aluminum is oxidized to form a film of the alumina. This finding can make clear the activated aluminum as a stored energy source for propellants and the good performance of aluminized explosives. The energies of DOS for N and O atoms of the NH2NO2 molecule match with those of Al atoms, and Al-O or Al-N bond forms easily at the corresponding energies range. The DOS projections on the N, O and Al atoms occur with obvious shift of peaks, which infers energy bands become broad and the interactions of chemical bonds are strengthened.