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Generalisation of the LEED approach to full potential + Molecular Dynamics approach

Generalisation of the LEED approach to full potential + Molecular Dynamics approach. Keisuke Hatada Dipartimento di Fisica, Universit à Camerino. 3d images of MT & NMT. Fe(CN) 6. Ge K-edge of GeCl 4. 1 Ge + 4 Cl + 38 EC (Empty cells).

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Generalisation of the LEED approach to full potential + Molecular Dynamics approach

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  1. Generalisation of the LEED approach to full potential + Molecular Dynamics approach Keisuke Hatada Dipartimento di Fisica, UniversitàCamerino

  2. 3d images of MT & NMT Fe(CN)6

  3. Ge K-edge of GeCl4 1 Ge + 4 Cl + 38 EC (Empty cells)

  4. For full potential case with homogeneous local harmonic oscillation LEED type averaging Fujikawa ‘93 Exact spherical wave case Hatada unpublished

  5. For simple anisotropic case Just The lowest contribution for anisotropy is l’=2

  6. Pair oscillation case oscillation should be treated as EXAFS like for all pairs of sites no correlation

  7. Correlation between displacements Δ Pair: R+δ R+δ Uncorrelated : 2Δ R Δ Probably small molecule neglecting the correlation is bad, but for solid might be less problematic

  8. Goal is for geometrical and electronic structure fitting of Nano cluster with ligands. => anisotropy of potential is big, many atoms, continuum state, thermal vibration, charge fluctuation, etc.

  9. Ni2+ in water – Ni Kedge average of thousands of MD models Calculations for some particular snapshots

  10. including the second shell average first shell average first + second shells average

  11. one shell fit two shells fit sizeable effects in the energy range 0 - 30 eV P. D’Angelo et al. JACS 128 (2006)

  12. L1 - L3 XAS data The water solvation of I- as in the previous case we analyze those data by MD snapshots generate by QM/MM and DFT methods in collaboration with Chergui’s group Hayakawa, Benfatto, unpublished

  13. We have used more than 1000 frames - three of them at L3 edge The calculation includes atoms (H and O) up to 7 Å Very disordered system!

  14. L3 Fits QM/MM DFT

  15. L1 Fits QM/MM DFT

  16. The QM/MM calculations reproduces better than DFT the experimental data for both L1 and L3 edges - Increasing the cluster size DFT becomes worse than QM/MM It seems that DFT introduces a partial order that is not verify in the reality

  17. Optical theorem Totally homogeneous vibration case,

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