Electronic, structural and thermodynamic properties of icosahedral free and supported Al clusters on Al surfaces from tight binding and classical molecular dynamics simulations

摘要

Icosahedral 55, 147 and 309 Al clusters were studied by means of tight binding zero temperature calculations and molecular dynamics simulations. We focus on the properties of the free and also of the deposited clusters on the low indexed Al surfaces. We found that the free Al clusters have lower melting temperatures and bulk moduli than the bulk material, while they exhibit enhanced low and high-energy phonon density of states. This behaviour is related mainly to the size of the clusters, while when deposited on the low index Al surfaces although they preserve their compactness, they reconstruct rapidly adopting the substrate's structure. In addition, the supported clusters do not alter significantly the surface vibrational behaviour, while when combining between them they recover a bulk like behaviour. In addition, the calculated electronic density of states revealed significant enhancement at energies around the Fermi level that was found to be due to charge transfer from the inner atoms towards the surface atoms.