C . Díaz 1 , J. K. Vincent 1 , K. M. Gangadharan Prasanna 1 ,

1.  N2 z r  y x Ru(0001) Dissociative adsorption of N2 on Ru(0001): a six-dimensional dynamics study C . Díaz1, J. K. Vincent1, K. M. Gangadharan Prasanna1, R. A. Olsen1, K. Honkala2, J. K. Nørskov2, G. J. Kroes1 1 Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands. 2 Center for Atomic-Scale Materials Physics, Department of Physics, Technical University of Denmark, DK-2800 Lyngby, Denmark. Why? Ruthenium (hcp) N2 + Ru(0001) • Ru is more active catalyst for • ammonia production than Fe • N2 dissociation is rate limiting step • Excellent prototype for direct • activated dissociative adsoprtion • (V*≈2.1 eV) Ru(0001) Previous experimental results Previous low-dimensional theoretical results • So < 0.01 at Ei up to 4.0 eV • So increases slowly for • Ei>Eb≈2.1 eV • Ev increase reaction more • than Ei • So almost independent of Ts • Only non-adiabatic • calculations can • reproduce experiment Our Methodology Our adiabatic 6D results PES (6D) • Ab initio data (Dacapo4 code) • DFT + RPBE GGA • Ultrasoft pseudopotential • Supercell model • Interpolation method5,6 • Modified Shepard interpolation • Grow method of Collins & co • - Non uniform ab initio data set • - Selection of points base on classical trajectories Conclusions • Good agreement between 6D adiabatic • calculations and the experiments • The inclusion of the 6D DOF of the N2 • in the dynamics is fundamental • Small, if any, non-adiabatic effects on • dissociation Quasi-classical dynamics • ZPE of N2 included • Monte-Carlo sample for initial condition • Integration of Hamilton equations • (1) Romm et al J. Phys. Chem. 101, 2213 (1997); (2) Diekhöner et al J. Chem. Phys. 115, 9028 (2001); (3) Diekhöner et al J. Chem. Phys. 117, 5018 (2002); • (4)http://dcwww.camp.dtu.dk/campos/Dacapo; (5) Crespos et al J. Chem Phys. 120, 2392 (2004); Collins, Theor. Chem. Acc. 108, 313 (2002)