Modelling superheating of small Ga and Al clusters 10   m Krista G. Steenbergen Nicola Gaston, Dmitri Schebarchov, Shaun ...
Overview <ul><li>Background </li></ul><ul><li>First-principles molecular dynamics </li></ul><ul><li>Multiple histogram spe...
Melting of Small Particles A. A. Shvartsburg, M. F. Jarrold. PRL  85 , 2530 (2000) Ph. Buffat, J.-P. Borel, PRA  13 , 2287...
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...
Bulk gallium
Bulk gallium E. Voloshina, K. Rosciszewski and B. Paulus, Phys. Rev. B  79 , 045113 (2009) S.C. Hendy and N. Gaston, Super...
Gallium Clusters <ul><li>Underlying mechanism for cluster superheating? </li></ul><ul><ul><ul><ul><ul><li>Role of structur...
Microcanonical Molecular Dynamics <ul><li>Constant NV E </li></ul>Positions of atoms/electrons Calculate forces E 1 10,000...
First-principles molecular dynamics <ul><li>VASP software package </li></ul><ul><li>Born-Oppenheimer MD </li></ul>Schrödin...
Computational Resources <ul><li>BlueGene/L </li></ul><ul><ul><li>University of Canterbury </li></ul></ul><ul><ul><li>2048 ...
Multiple Histogram Specific Heats
Cluster Melting Curve – Ga 20 Ga 20 Ga 20 + S. Krishnamurty et al. . PRB  73 , 045406 (2006)
Cluster Melting Curves – Ga 20 + Ga 20 + , less accurate potential than Ga 20 Ga 20 + S. Krishnamurty et al. . PRB  73 , 0...
Cluster Melting Curves – Al 20 C. M. Neal et al. . PRB  76 ,  054113  (2007) 0 K 600 K 1200 K Al 20 Al 20 +
Cluster Melting Curves
Cluster Melting Curve – Ga 33 Ga 33 Ga 33 + G.A. Breaux et al, J. Am. Chem. Soc.  126 , 8628-9 (2004)
Structural Analysis <ul><li>Time, temp or energy, N x atoms, structure measure </li></ul>250 K 800 K 1150 K
Structural Analysis Ga 20 , 600 K Ga 20 , 1150 K
Future Work <ul><li>Continue MD on more cluster sizes </li></ul><ul><ul><li>Ga n  and Al n  for n=20-34 </li></ul></ul><ul...
Many Thanks <ul><li>Dr. Nicola Gaston and Dr. Shaun C. Hendy </li></ul><ul><li>Dmitri Schebarchov and Amanda Parker </li><...
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16.00 o5 k steenbergen

  1. 1. Modelling superheating of small Ga and Al clusters 10  m Krista G. Steenbergen Nicola Gaston, Dmitri Schebarchov, Shaun C. Hendy
  2. 2. Overview <ul><li>Background </li></ul><ul><li>First-principles molecular dynamics </li></ul><ul><li>Multiple histogram specific heat curves </li></ul><ul><li>Structural analysis </li></ul>Dr. Gaston Drs. Schebarchov and Hendy
  3. 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. 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. 5. Bulk gallium
  6. 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. 7. Gallium Clusters <ul><li>Underlying mechanism for cluster superheating? </li></ul><ul><ul><ul><ul><ul><li>Role of structure? </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Dimeric nature? </li></ul></ul></ul></ul></ul>
  8. 8. Microcanonical Molecular Dynamics <ul><li>Constant NV E </li></ul>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. 9. First-principles molecular dynamics <ul><li>VASP software package </li></ul><ul><li>Born-Oppenheimer MD </li></ul>Schrödinger Newton electrons ions Monte Carlo “Dice Roll”
  10. 10. Computational Resources <ul><li>BlueGene/L </li></ul><ul><ul><li>University of Canterbury </li></ul></ul><ul><ul><li>2048 processors </li></ul></ul><ul><li>Carbon Cluster </li></ul><ul><ul><li>Argonnne National Laboratory </li></ul></ul><ul><ul><li>2784 processors </li></ul></ul><ul><li>Kakapo Cluster </li></ul><ul><ul><li>Industrial Research Ltd. </li></ul></ul><ul><ul><li>128 processors </li></ul></ul><ul><li>BlueGene/P </li></ul><ul><ul><li>UofC </li></ul></ul><ul><ul><li>8192 processors (!!) </li></ul></ul>
  11. 11. Multiple Histogram Specific Heats
  12. 12. Cluster Melting Curve – Ga 20 Ga 20 Ga 20 + S. Krishnamurty et al. . PRB 73 , 045406 (2006)
  13. 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. 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. 15. Cluster Melting Curves
  16. 16. Cluster Melting Curve – Ga 33 Ga 33 Ga 33 + G.A. Breaux et al, J. Am. Chem. Soc. 126 , 8628-9 (2004)
  17. 17. Structural Analysis <ul><li>Time, temp or energy, N x atoms, structure measure </li></ul>250 K 800 K 1150 K
  18. 18. Structural Analysis Ga 20 , 600 K Ga 20 , 1150 K
  19. 19. Future Work <ul><li>Continue MD on more cluster sizes </li></ul><ul><ul><li>Ga n and Al n for n=20-34 </li></ul></ul><ul><li>Structural analysis </li></ul><ul><ul><li>Common Neighbor Analysis </li></ul></ul><ul><ul><li>Lindemann Index </li></ul></ul>
  20. 20. Many Thanks <ul><li>Dr. Nicola Gaston and Dr. Shaun C. Hendy </li></ul><ul><li>Dmitri Schebarchov and Amanda Parker </li></ul><ul><li>The Marsden Fund </li></ul><ul><li>MacDiarmid Institute for Advanced Materials and Nanotechnology </li></ul><ul><li>Industrial Research, Ltd. </li></ul><ul><li>BlueFern </li></ul><ul><li>Argonne National Laboratory </li></ul>

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