DIFFUSION OF NH2NO2 ON Al (111) SURFACE: MOLECULAR DYNAMICS STUDY

Abstract

The diffusion of NH2NO2 molecules on the Al (111) surface has been investigated by the molecular dynamics (MD) method. The influence of temperature and pressure on their diffusion was studied. The binding energies decrease obviously with the temperature increasing because non-bonding interaction between Al atoms and NH2NO2 molecules weakens. As the temperature increases, the value of the first peak for radial distribution function (RDF) of Al–N and Al–O bond decreases. Diffusion rates increase with temperature increasing whereas they first decrease, then increase with pressure increasing below 450[Formula: see text]K. The diffusion activation energy of NH2NO2 molecules on the Al surface is among 13.8–18.1[Formula: see text]kJ[Formula: see text][Formula: see text][Formula: see text]mol[Formula: see text] at the pressure from 0[Formula: see text]GPa to 10.0[Formula: see text]GPa, which indicates that NH2NO2 molecules diffuse easily on the Al surface and the influence of pressure on diffusion of NH2NO2 molecules on the Al surface is small. At the low temperature (i.e. below 300[Formula: see text]K), the NH2NO2 molecules are mainly adsorbed on the Al surface by intramolecular and intermolecular interactions, while NH2NO2 molecules diffuse on the Al surface and surface Al atoms deviate a little from their original position above the moderate temperature (i.e. above 350[Formula: see text]K). These results indicate that the influence of temperature on the diffusion of NH2NO2 molecules on the Al surface is large whereas the influence of pressure on the diffusion is relatively small.