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16.00 o5 k steenbergen

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Research 4: K Steenbergen

Research 4: K Steenbergen

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  • 1. Modelling superheating of small Ga and Al clusters 10  m Krista G. Steenbergen Nicola Gaston, Dmitri Schebarchov, Shaun C. Hendy
  • 2. Overview
    • Background
    • First-principles molecular dynamics
    • Multiple histogram specific heat curves
    • Structural analysis
    Dr. Gaston Drs. Schebarchov and Hendy
  • 3. Melting of Small Particles A. A. Shvartsburg, M. F. Jarrold. PRL 85 , 2530 (2000) Ph. Buffat, J.-P. Borel, PRA 13 , 2287 (1976) T m  1/R
  • 4. Small Al and Ga clusters G.A. Breaux et al, J. Am. Chem. Soc. 126 , 8628-9 (2004) C. M. Neal, A. K. Starce, M. F. Jarrold, PRB 76 , 054113 (2007)
  • 5. Bulk gallium
  • 6. Bulk gallium E. Voloshina, K. Rosciszewski and B. Paulus, Phys. Rev. B 79 , 045113 (2009) S.C. Hendy and N. Gaston, Superheating in Nanoparticles, The Handbook of Nanophysics (2010)
  • 7. Gallium Clusters
    • Underlying mechanism for cluster superheating?
            • Role of structure?
            • Dimeric nature?
  • 8. Microcanonical Molecular Dynamics
    • Constant NV E
    Positions of atoms/electrons Calculate forces E 1 10,000 MD steps E 2 10,000 MD steps E 3 10,000 MD steps … E 19 10,000 MD steps
  • 9. First-principles molecular dynamics
    • VASP software package
    • Born-Oppenheimer MD
    Schrödinger Newton electrons ions Monte Carlo “Dice Roll”
  • 10. Computational Resources
    • BlueGene/L
      • University of Canterbury
      • 2048 processors
    • Carbon Cluster
      • Argonnne National Laboratory
      • 2784 processors
    • Kakapo Cluster
      • Industrial Research Ltd.
      • 128 processors
    • BlueGene/P
      • UofC
      • 8192 processors (!!)
  • 11. Multiple Histogram Specific Heats
  • 12. Cluster Melting Curve – Ga 20 Ga 20 Ga 20 + S. Krishnamurty et al. . PRB 73 , 045406 (2006)
  • 13. Cluster Melting Curves – Ga 20 + Ga 20 + , less accurate potential than Ga 20 Ga 20 + S. Krishnamurty et al. . PRB 73 , 045406 (2006)
  • 14. Cluster Melting Curves – Al 20 C. M. Neal et al. . PRB 76 , 054113 (2007) 0 K 600 K 1200 K Al 20 Al 20 +
  • 15. Cluster Melting Curves
  • 16. Cluster Melting Curve – Ga 33 Ga 33 Ga 33 + G.A. Breaux et al, J. Am. Chem. Soc. 126 , 8628-9 (2004)
  • 17. Structural Analysis
    • Time, temp or energy, N x atoms, structure measure
    250 K 800 K 1150 K
  • 18. Structural Analysis Ga 20 , 600 K Ga 20 , 1150 K
  • 19. Future Work
    • Continue MD on more cluster sizes
      • Ga n and Al n for n=20-34
    • Structural analysis
      • Common Neighbor Analysis
      • Lindemann Index
  • 20. Many Thanks
    • Dr. Nicola Gaston and Dr. Shaun C. Hendy
    • Dmitri Schebarchov and Amanda Parker
    • The Marsden Fund
    • MacDiarmid Institute for Advanced Materials and Nanotechnology
    • Industrial Research, Ltd.
    • BlueFern
    • Argonne National Laboratory

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