Reply to “Comment on ‘Negative heat capacities and first order phase transition in nuclei’ ”

The Clapeyron equation is adequate in describing the properties of any finite Van der Waals–like system, including Ising-Potts models. Coulomb interaction destroys the generality of solutions for finite systems, and the resulting metastability prevents meaningful application of statistical mechanics. The effective closure of unstable channels by high barriers allows for negative heat capacities only for $A<30$.

Figure 1

The difference between the mass of ${}^{207}\mathrm{Pb}$ and its three fragment “ground” state calculated via the liquid drop model with only volume and surface terms (dotted line) and volume, surface, and Coulomb terms (dashed line). Note that the three fragments previously described have an infinite separation. The solid line includes the Coulomb interaction between fragments and describes an “effective” $Q$ value as a function of fragment separation. $R_{\text{scale}}=1$ represents the three fragments touching at closest separation in a triangle configuration.

Figure 2

The average cluster size is plotted as a function of $E^{*}$, excitation energy for the EOS data [5]. The arrow shows the approximate location of the critical point. The right panel shows the average cluster size as a function of temperature for the $d=2$ Ising model for the indicated lattice sizes.