A complete description and understanding of the dynamics of simple molecules impinging on metallic surfaces is important for many technologically relevant applications such as heterogenous catalysis, just to name one.
In a recent article, some of the authors presented the calculation of the six-dimensional potential energy surface (6D-PES) for N2 molecules on W(110). Results were obtained by means of density functional theory together with a corrugation reduction procedure [1]. The molecule's dissociative adsoption was studied within a classical dynamics frame and two distinct channels were found that contributed to the dissociation process, namely a direct one and an indirect one. The theoretical results for the sticking coefficient at low coverage compared well with experimental measurements at 800K, except for the low incident-energy region where the indirect channel prevailed.
In this presentation, the dissociation dynamics for this system (N2 on W(110) ) in the low energy range is shown to be very sensitive to the details of the potential energy surface. In order to illustrate this, the full multidimensional PES is re-calculated considering a different exchange-correlation functional and the effects of this change in the dissociation dynamics are analyzed and discussed. In particular, the weight of the indirect channel is found to drastically diminish in the new calculation. Our results lead us to discuss the role of dynamical studies in the optimization of density functional theory calculations in this kind of problems.
[1] M. Alducín, R. Diez Muiño, H.F. Busnengo, and A. Salin, Phys. Rev. Lett. 97, 056102 (2006) |