The thermodynamic properties of clusters containing 55, 135, and 429 atoms have been calculated using the molecular dynamics method. Structural and vibrational properties of the clusters were examined at different temperatures in both the solid and the liquid phase. The nature of the melting transition was investigated, and a number of properties, such as melting temperature, latent heat of melting, and premelting phenomena, were found to vary with cluster size. These properties were also found to depend on the structure of the solid phase. In this phase the configuration of lowest free energy was found to be icosahedral in the 55-atom system and face centered cubic for the two larger systems.

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The dynamic aspects of the dislocation theory of melting have been examined. A new theory, based on rate equations for the formation and annihilation of dislocation segments, is proposed. The instability temperature for the infinite crystal case is deduced, and a relationship between this temperature and the thermodynamic melting temperature is quantitatively established. The theory is tested against experimental melting temperatures and shows a fair agreement. The agreement might be improved if precise information concerning the dislocation formation mechanism could be established for the tested elements.

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