Temperature Dependence of the Polarizability of Sodium Clusters

We calculate the static dipole polarizability at finite temperature of sodium clusters of size 8, 20, 40, 55, 93, and 139 using an extended Thomas-Fermi description of the valence electrons. We find polarizabilities at 300 K that are roughly 15% greater than at 0 K, consistent with discrepancies between theoretical polarizabilities at 0 K and measured polarizabilities. We predict that a sharp rise in the polarizability, of about 5%, occurs for sizes of 55 and 139 when the cluster melts, offering the possibility of an alternative method for measuring cluster melting points.