Dissociative adsorption of N2 on the W(1 0 0) surface

We construct a full 6D potential energy surface (PES) from ab initio calculations, at the DFT/GGA level, for the interaction of N2 with the frozen (1 0 0) surface of tungsten. Our ab initio calculations show complex non-activated 6D paths to dissociation, whereas all 2D cuts show an activation barrier. We use the 6D PES in classical trajectory calculations under normal incidence. The results of the dynamics confirm the non-activated behaviour of the dissociative adsorption process. The large value of the dissociation probability at low energies (which is one for zero impact energy) is due to a “bow net” effect: the molecule can only approach/leave the surface close to the top site in near vertical orientation. The latter effect explains how the complex path leading to dissociation is compatible with the large sticking probability. Dynamic trapping plays a key role in the whole energy range considered in this work.