Why do gallium clusters have a higher melting point than the bulk? - art. no. 135506

Density functional molecular dynamical simulations have been performed on Ga-17 and Ga-13 clusters to understand the recently observed higher-than-bulk melting temperatures in small gallium clusters [G. A. Breaux et al., Phys. Rev. Lett. 91, 215508 (2003)]. The specific-heat curve, calculated with the multiple-histogram technique, shows the melting temperature to be well above the bulk melting point of 303 K, viz., around 650 and 1400 K for Ga-17 and Ga-13, respectively. The higher-than-bulk melting temperatures are attributed mainly to the covalent bonding in these clusters, in contrast with the covalent-metallic bonding in the bulk.