Ab initio molecular dynamics study of heterogeneous nitric acid decomposition reactions on graphite surfaces

The goal of the present work is to unravel the role of the soot surface on the decomposition of nitric acid as a possible renoxification process. We study the monomolecular and the bimolecular decomposition reactions of gas-phase nitric acid on a pristine and on a defective graphite surface as a simple model of the interactions occurring on the surface of atmospheric soot particles. The metadynamics method is employed to reproduce the atomistic details of the reaction paths for both monomolecular and bimolecular processes. Several different intermediate states, which are encountered along the reactive trajectory, are analyzed, and the role of the surface in catalyzing the reactions is discussed.