Critical analysis of negative heat capacity in nanoclusters

It is shown that "negative heat capacity" in nanoclusters is an artifact of applying equilibrium thermodynamic formalism on a "small" system trapped in a metastable state differing from true thermodynamic equilibrium. Trapping occurs due to high-energy barriers separating different regions of the cluster phase space, particularly for cluster sizes near the magic numbers corresponding to closed geometrical shells. Trapping may occur in either the canonical or microcanonical ensemble, but it is unavoidable in the microcanonical and can lead to a dependence on initial conditions of the determined cluster properties. Copyright (C) EPLA, 2007.