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Molecular polarizability of semiconductor clusters and nanostructures

Francisco Torrens*

Institut Universitari de Ciència Molecular, Universitat de València,
E-46100 Burjassot (València), Spain

This is an abstract for a presentation given at the
Ninth Foresight Conference on Molecular Nanotechnology.
There will be a link from here to the full article when it is available on the web.

 

The role of size in modifying the properties of a material has not been exploited until recently. On the basis of interatomic potentials, the structure of some clusters are special. Nanocrystalline powders can be used to synthesize materials with physical processing such as sintering. In previous papers, fullerenes, Sc clusters, Sc-cluster endohedral fullerenes,1 graphite models and Sc hexagonal close packing were studied.2 Here, the following semimetallic clusters have been calculated: Si/Ge/GaAs. The interacting induced dipoles polarization model implemented in program PAPID3 is used for the calculation of the molecular dipole-dipole polarizability dipole-dipole polarizability. The method is tested with Sin, Gen (n less than or equal 10) and GanAsm (n,m less than or equal 4) small clusters. Program PAPID has been used for the calculation of the dipole-dipole polarizability dipole-dipole polarizability, with the interacting-induced-dipoles polarization model that calculates tensor effective anisotropic point polarizabilities1,2 by the method of Applequist et al.. The bulk limit for the polarizability is estimated from the Clausius-Mossotti relationship. The results for the polarizability are in agreement with reference calculations from J. R. Chelikowsky carried out within the density functional theory.4 The clusters are all more polarizable than what one might have inferred from the bulk polarizability. Previous experimental work have yielded the opposite trend for somewhat larger clusters. On varying the number of atoms, the clusters show numbers indicative of particularly polarizable structures. The polarizability trend for these clusters as a function of size is different from what one might have expected. The high polarizability of small clusters is attributed to arise from dangling bonds at the surface of the cluster.

References
  1. Torrens, F. Microelectron. Eng. 2000, 51-52, 613.
  2. Torrens, F. Molecules 2001, 6, 496.
  3. Voisin, C.; Cartier, A.; Rivail, J.-L. J. Phys. Chem. 1992, 96, 7966.
  4. Chelikowsky, J. R. The electronic and structural properties of semiconductor clusters and nanostructures, Res. Rep. UMSI 97/132, University of Minnesota Supercomputing Institute, 1997.

Abstract in RTF format 27,640 bytes


*Corresponding Address:
Francisco Torrens
Institut Universitari de Ciència Molecular, Universitat de València
Dr. Moliner 50, E-46100 Burjassot (València), Spain
phone: 34.963983182
fax: 34.963983156
email: Francisco.Torrens@uv.es
http://www.uv.es/~icmol



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