Negative heat capacities and first order phase transitions in nuclei

Abstract

Anomalous negative heat capacities have been claimed as indicators of first-order phase transitions in finite systems in general, and for nuclear systems in particular. A thermodynamic approach allowing for all Q-value terms is used to evaluate heat capacities in finite van der Waals fluids and finite lattice systems in the coexistence region. Fictitious large effects and negative heat capacities are observed in lattice systems when periodic boundary conditions are introduced. Small anomalous effects are predicted for small drops and for finite lattice systems. A straightforward application of the analysis to nuclei shows that negative heat capacities cannot be observed for $Ag60.$