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

Finite temperature analysis of cluster structures is used to identify signatures of the low-temperature polymorphs of gallium, based on the results of first-principle Born-Oppenheimer molecular dynamics simulations. Pre-melting structural transitions proceed from either the beta- and/or the delta-phase to the gamma- or delta-phase, with a size-dependent phase progression. We relate the stability of each isomer to the electronic structures of the different phases, giving new insight into the origin of polymorphism in this complicated element.