# Laboratoire Collisions Agrégats Réactivité - UMR5589

Université Paul Sabatier - Bat. 3R4 - 118 route de Narbonne 31062 Toulouse Cedex 09, France

## A two-state model analysis of the melting of sodium clusters : Insights in the enthalpy-entropy compensation

Experimental melting temperatures and associated latent heats of size-selected sodium
clusters are analyzed in the frame of a two-state model of melting. The strong variations of these
quantities as a function of size make clusters an excellent benchmark for testing speculative ideas
about melting. The relation between cohesive energy of clusters and their latent heat of melting
is demonstrated, and a correlation between cohesive energy and vibrational frequency in the solid
state is found. It is shown that this relation may throw light on the enthalpy-entropy compensation,
which is observed in a variety of systems undergoing a first-order phase transition. A relation is
established between the Lindemann melting criterion, the variation of the vibrational frequency
with the cohesive energy, and the enthalpy-entropy compensation.

doi : 10.1209/0295-5075/92/13004

Voir en ligne : EPL 92 (2010) 13004