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ACCURACY OF DFT CALCULATIONS IN THE DISSOCIATION OF N 2 /W(110) ‏

ACCURACY OF DFT CALCULATIONS IN THE DISSOCIATION OF N 2 /W(110) ‏. G.A. Bocan , R. Díez Muiño, M. Alducin, H.F. Busnengo, and A. Salin. Donostia International Physics Center (DIPC) San Sebastián, Spain. MOLECULAR DYNAMICS. MOLECULAR DYNAMICS. Direct Reflection. MOLECULAR DYNAMICS.

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ACCURACY OF DFT CALCULATIONS IN THE DISSOCIATION OF N 2 /W(110) ‏

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  1. ACCURACY OF DFT CALCULATIONS IN THE DISSOCIATION OF N2/W(110)‏ G.A. Bocan, R. Díez Muiño, M. Alducin, H.F. Busnengo, and A. Salin Donostia International Physics Center (DIPC) San Sebastián, Spain

  2. MOLECULAR DYNAMICS

  3. MOLECULAR DYNAMICS Direct Reflection

  4. MOLECULAR DYNAMICS Direct dissociative sticking

  5. MOLECULAR DYNAMICS Dynamic Trapping

  6. Build the 6D Potential Energy Surface (PES)‏ + Classical molecular dynamics DFT calculations (VASP): Grid of 5610 6D points The PES Interpolation: Corrugation Reducing Procedure HOW AND WHY System: N2 / W(110) (large crystallographic anisotropies)‏ DFT not exact!! Only reflection & dissociative sticking allowed Frozen surface Adiabatic approximation XC modeled by a GGA functional

  7. DYNAMICS: PW91 vs. RPBE Theoretical prediction (PW91 XC functional in the PES)‏ Alternative RPBE XC functional Better fit to experimental chemisorption energies Better description very near the metallic surface Better dynamics?? Theoretical prediction (RPBE XC functional in the PES)‏ • H.E. Pfnür et al., JCP 85 7452 (1986)‏ • C.T. Rettner et al., JCP 93, 1442 (1990)‏ M. Alducin et al., PRL 97, 056102 (2006)‏

  8. NORMAL INCIDENCE PW91 RPBE Ei = 0.4 eV, 5000 trajectories

  9. 60o INCIDENCE PW91 RPBE Ei = 0.9 eV, 5000 trajectories

  10. CONCLUSIONS RPBE higher medium distance barriers make it more difficult for incoming trajectories to reach the precursor well, thus ensuring a better fit to experiments in normal incidence but also a poor prediction for the 60o incidence case. The differences between RPBE and PW91 results are a measure of the PES DFT calculation accuracy.

  11. THE END (Thank you for your attention!)‏

  12. Top Hollow Bridge Long Top-Hollow BACK TO THE PES

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