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   COLLOQUIUM OF THE LABORATORY FOR COMPUTER DESIGN OF MATERIALS
                   School of Computational Sciences
                           (CSI 898-Sec 001)
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Temperature Dependence of the  Polarizability of Sodium Clusters

                      Rajendra R. Zope
School of Computational Sciences, George Mason University

Metallic clusters are interesting objects with properties that are 
often very different from the atomic and bulk limits. One of the 
pioneering experiments which triggered the interest in the study of 
metallic clusters was the measurement of the static dipole 
polarizabilities of sodium clusters. The measured polarizabilites
were found to be significantly larger than those calculated 
theoretically at zero temperature.  We present the results of the 
static dipole polarizability of sodium clusters of sizes 8, 20, 40, 
55, 93, and 139 calculated at finite temperatures by an ab-initio 
molecular dynamics with an extended Thomas-Fermi description
of the valence electrons.  We find polarizabilities at 300 K that are 
roughly 15% greater than those at 0 K, consistent with discrepancies 
between the theoretical and experimental approaches. When clusters of 
sizes 55 and 139 melt, we predict that a sharp rise of the 
polarizability occurs. Therefore, this mechanism offers the 
possibility to develop a novel method for measuring the cluster 
melting temperature.

                         Monday , February 4, 2002
                                  4:30 pm
                        Room 206, Science & Tech. I

Refreshments will be served at 4:15 PM.
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Find the schedule at http://www.csi.gmu.edu/lcdm/seminar/schedule.html