The role of exchange correlation functionals in the dynamics of N2 dissociation on W surfaces: Probing RPBE and PW91

G.A. BOCAN; R.DÍEZ MUIÑO; M. ALDUCIN; H.F. BUSNENGO; A. SALIN

Dublín, Irlanda

Conferencia; XIV International Conference on Solid Films and Surfaces; 2008

ICSFS

<!-- @page { margin: 0.79in } P { margin-bottom: 0.08in } --> Resumen State of the art theoretical studies of the dynamics of molecules impinging on metal surfaces are based on density functional theory (DFT) calculations of multidimensional potential energy surfaces (PESs). A generalized gradient approximation (GGA) functional is often used to account for exchange-correlation effects [1,2]. By contrast with the computation of chemisorption energies, whose accuracy is determined by only a small region of the PES, dynamical processes test PES properties over a much larger volume. In the present work, we show that the calculated reactivity for N2 molecules impinging on either W(100) or W(110) strongly depends on the choice of GGA exchange-correlation functional: results for the dissociation probability when using the PW91 [3,4,5] or RPBE [6] functionals are significantly different. We carry out a systematic comparison between the dynamics determined by the respective PESs. We conclude that, even though there is evidence that the RPBE provides a better description when the molecule is close to the surface (as observed for adsorption energies), it seems to fail badly in the low density region far from the surface, of key importance for the dynamics of molecule/surface interactions. [1] J.P. Perdew et al., Phys. Rev. B 46, 6671 (1992). [2] B. Hammer, L.B. Hansen, and J.K. Nørskov, Phys. Rev. B 59, 7413 (1999). [3] G. Volpilhac and A. Salin, Surf. Sci. 556, 129 (2004). [4] M. Alducin, R. Díez Muiño, H.F. Busnengo, and A. Salin, J. of Chem. Phys. 125, 144705 (2006). [5] M. Alducin, R. Díez Muiño, H.F. Busnengo, and A. Salin, Phys. Rev. Lett 97, 056102 (2006). [6] G.A. Bocan, R. Díez Muiño, M. Alducin, H.F. Busnengo, and A. Salin, J. of Chem. Phys., in press.