Geometrically induced melting variation in gallium clusters from first principles

Cluster melting: new, limiting, and liminal phenomena

“…In this work, it was shown that the most stable ground state structures may indeed be sensitive to electronic shell closings, as predicted within the jellium model. Earlier work on the same system of gallium clusters had already demonstrated how geometric effects may sensitively affect the melting behaviour of a clusters [52]. However at temperatures just below the melting temperature, structures other than the ground state structure may be quite dominant: where this is the case, it is clear that ground state geometries may fail to explain melting temperature variations with size [51].…”

“…The use of DFT based BOMD for these small gallium clusters has demonstrated the ability of these calculations to replicate the experimental findings, both with respect to the melting temperature variations and the nature of melting in those cases where multiple transitions are observed [51,52,83,84]. As expected, the complex phase diagram of gallium leads to many interesting features in the electronic structure as a function of temperature, and these have been isolated through statistical analysis of the dynamic structures [84] to provide evidence of the relative stability of different solid phases -related to the various low temperature polymorphs of gallium (β, δ, or γ ), but never to the dimeric standard (α) phase -at finite temperature [51].…”

“…A first indication of the importance of structure was presented by Joshi, who identified structural features in more highly ordered clusters that correlate with a stronger peak in the heat capacity, and a more clearly first-order like phase-transition [80]. The existence of covalent bonding in the bulk form of gallium has led to searches for electronic signatures of covalency in the clusters [81], and in many cases, some correlation of structural change with melting temperature variation has been demonstrated to be possible [52,82].…”

Quantum Size Effects in the Size–Temperature Phase Diagram of Gallium: Structural Characterization of Shape‐Shifting Clusters

“…Herein, we demonstrate the importance of analyzing structural changes and stability at a finite temperature. Based on first‐principles molecular dynamics (MD) simulations that produce specific heat curves in excellent agreement with the experimental data,10, 13 we present details of the size–temperature phase diagram for unsupported gallium cluster cations containing 32–36 atoms. Our structural assignments are based on the persistence of a given motif over trajectory time, not on quenched isomers.…”

“…We obtained specific heat curves by histogram reweighting technique of the multiple histogram method 18. Previous work summarizes the comparison between our simulated specific heat curves11, 13 and the experimental curves 10…”