Cluster melting: New, limiting, and liminal phenomena

Abstract

The thermodynamic behaviour of clusters and nanoscale structures is both a challenge to the statistical basis of the theory, and of paramount importance to experiment. In this review, the competing influences that determine the melting temperature and behaviour of small atomic clusters is discussed, with reference to both experiment and theory. The liminal spaces between solid and liquid, the non-scaling and scaling regimes, and the metallic and non-metallic states are discussed, and presented as a primary cause of the emergence of new phenomena. Particular emphasis is given to recent theoretical work that combines each of these liminal regions and enables, through first principles calculations of dynamic atomic interactions in Born Oppenheimer molecular dynamics, the explanation of greater than bulk melting temperatures in certain atomic cluster systems. Some perspective is also given on the important questions in nanoscale thermodynamics that remain to be addressed.