Magic Melters' Have Geometrical Origin

TL;DR

This study uses ab initio molecular dynamics to explore how the ground state geometries of small Gallium clusters influence their heat capacities, revealing a size-sensitive effect that is likely common in small clusters.

Contribution

It demonstrates that the size-sensitive heat capacities in small clusters originate from differences in their ground state geometries, supported by extensive simulations.

Findings

Heat capacities are highly sensitive to cluster size and geometry.

Ground state geometry determines heat capacity characteristics.

Size sensitivity is a generic feature of small clusters.

Abstract

Recent experimental reports bring out extreme size sensitivity in the heat capacities of Gallium and Aluminum clusters. In the present work we report results of our extensive {\it ab initio} molecular dynamical simulations on Ga$_{30}$ and Ga$_{31}$, the pair which has shown rather dramatic size sensitivity. We trace the origin of this size sensitive heat capacities to the relative order in their respective ground state geometries. Such an effect of nature of the ground state on the characteristics of heat capacities is also seen in case of small Gallium and Sodium clusters indicating that the observed size sensitivity is a generic feature of small clusters.