Influence of electronic and geometric properties on melting of sodium clusters

Systematics of the melting transition for sodium clusters with 40-355 atoms has been studied with both a initio and semiclassical molecular dynamics simulations. The melting temperatures obtained with an ab initio method for Na-55(+) and Na-93(+) correlate well with the experimental results. The semiclassically determined melting temperatures show similarities with the experimentally determined ones in the size region from 55 to 93 and near size 142, and the latent beat in the size region from 55 to 139, but not elsewhere in the size region studied. This indicates that the nonmonotonical melting behavior observed experimentally cannot be fully explained by geometrical effects. The semiclassically determined melting temperature and the latent heat correlate quite well, indicating that they respond similarly to changes in cluster geometry and size. Similarly, the binding energy per atom seems to correlate with the melting temperature and the latent heat of fusion.