Size--sensitive melting characteristics of gallium clusters: Comparison of Experiment and Theory for Ga${}_{17}{}^{+}$ and Ga${}_{20}{}^{+}$

Abstract

Experiments and simulations have been performed to examine the finite-temperature behavior of Ga${}_{17}{}^{+}$ and Ga${}_{20}{}^{+}$ clusters. Specific heats and average collision cross sections have been measured as a function of temperature, and the results compared to simulations performed using first principles Density--Functional Molecular--Dynamics. The experimental results show that while Ga${}_{17}{}^{+}$ apparently undergoes a solid--liquid transition without a significant peak in the specific--heat, Ga${}_{20}{}^{+}$ melts with a relatively sharp peak. Our analysis of the computational results indicate a strong correlation between the ground--state geometry and the finite--temperature behavior of the cluster. If the ground--state geometry is symmetric and "ordered" the cluster is found to have a distinct peak in the specific--heat. However, if the ground--state geometry is amorphous or "disordered" the cluster melts without a peak in the specific--heat.

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References in corpus (3)

• Why do gallium clusters have a higher melting point than the bulk?
• Thermodynamics of tin clusters
• Thermodynamics of Na_8 and Na_{20} clusters studied with ab-initio electronic structure methods

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