Ab initio molecular dynamical investigation of the finite temperature behavior of the tetrahedral Au19 and Au20 clusters

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dc.contributor.author Krishnamurty, S
dc.contributor.author Shafai, GS
dc.contributor.author Kanhere, DG
dc.contributor.author De Bas, BS
dc.contributor.author Ford, MJ
dc.date.accessioned 2009-12-21T02:28:27Z
dc.date.issued 2007-10-25
dc.identifier.citation Journal of Physical Chemistry A, 2007, 111 (42), pp. 10769 - 10775
dc.identifier.issn 1089-5639
dc.identifier.other C1 en_US
dc.identifier.uri http://hdl.handle.net/10453/3501
dc.description.abstract Density functional molecular dynamics simulations have been carried out to understand the finite temperature behavior of Au19 and Au 20 clusters. Au20 has been reported to be a unique molecule having tetrahedral geometry, a large HOMO-LUMO energy gap, and an atomic packing similar to that of the bulk gold (Li, J.; et al. Science 2003, 299, 864). Our results show that the geometry of Au19 is exactly identical with that of Au20 with one missing corner atom (called a vacancy). Surprisingly, our calculated heat capacities for this nearly identical pair of gold clusters exhibit dramatic differences. Au20 undergoes a clear and distinct solid-like to liquid-like transition with a sharp peak in the heat capacity curve around 770 K. On the other hand, Au19 has a broad and flat heat capacity curve with continuous melting transition. This continuous melting transition turns out to be a consequence of a process involving a series of atomic rearrangements along the surface to fill in the missing corner atom. This results in a restricted diffusive motion of atoms along the surface of Au19 between 650 to 900 K during which the shape of the ground state geometry is retained. In contrast, the tetrahedral structure of Au20 is destroyed around 800 K, and the cluster is clearly in a liquid-like state above 1000 K. Thus, this work clearly demonstrates that (i) the gold clusters exhibit size sensitive variations in the heat capacity curves and (ii) the broad and continuous melting transition in a cluster, a feature that has so far been attributed to the disorder or absence of symmetry in the system, can also be a consequence of a defect (absence of a cap atom) in the structure. © 2007 American Chemical Society.
dc.language eng
dc.relation.hasversion Accepted manuscript version
dc.relation.isbasedon 10.1021/jp075896+
dc.title Ab initio molecular dynamical investigation of the finite temperature behavior of the tetrahedral Au19 and Au20 clusters
dc.type Journal Article
dc.parent Journal of Physical Chemistry A
dc.journal.volume 42
dc.journal.volume 111
dc.journal.number en_US
dc.journal.number 42 en_US
dc.publocation Washington DC, USA en_US
dc.identifier.startpage 10769 en_US
dc.identifier.endpage 10775 en_US
dc.cauo.name SCI.Physics and Advanced Materials en_US
dc.conference Verified OK en_US
dc.for 0306 Physical Chemistry (Incl. Structural)
dc.personcode 020323
dc.percentage 100 en_US
dc.classification.name Physical Chemistry (incl. Structural en_US
dc.classification.type FOR-08 en_US
pubs.embargo.period Not known
pubs.organisational-group /University of Technology Sydney
pubs.organisational-group /University of Technology Sydney/Faculty of Science
pubs.organisational-group /University of Technology Sydney/Strength - Materials and Technology for Energy Efficiency
utslib.copyright.status Closed Access
utslib.copyright.date 2015-04-15 12:23:47.074767+10
pubs.consider-herdc true
utslib.collection.history General (ID: 2)


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