From DFT cluster calculations to molecular dynamics simulation of N2 formation on a silica model surface

B3LYP-DFT electronic structure cluster calculations have been performed to evaluate the adsorption properties of N and N2 interacting with SixOy clusters in a given adsorption site. To check the convergence of the calculated binding energy, clusters of different size were used in the calculations. As expected, the N atom is chemisorbed, Eb?2.75eV, while N2 is weakly physisorbed. The ab initio results were used to build three PES of the LEPS-type having different activation barrier. The obtained PES have been used in the semiclassical scattering equations and the dynamics of the N2 formation after atom recombination on a model silica surface was studied in great detail.