Specific heats of clusters near a phase transition: Energy partitions among internal modes

This Letter proposes a way to answer the question of how energy is shared by internal degrees of freedom, when nanoaggregates are heated and undergo phase transitions. Microcanonical molecular dynamics simulations of clusters of 13 and 55 atoms are assisted by our analysis of energy partitions in terms of contributions connected with groups of degrees of freedom of the nanoaggregates. The merit of the partition is shown to be the effective decoupling of modes, demonstrating its role as an indicator of the phase transitions and its perspective use for statistical mechanical approaches by the identification of active degrees of freedom.