  Caloric curves have traditionally been derived within the microcanonical
ensemble via dS/dE=1/T or within the canonical ensemble via E=T^2*d(ln Z)/dT.
In the thermodynamical limit, i.e., for large systems, both caloric curves give
the same result. For small systems like nuclei, the two caloric curves are in
general different from each other and neither one is reasonable. Using
dS/dE=1/T, spurious structures like negative temperatures and negative heat
capacities can occur and have indeed been discussed in the literature. Using
E=T^2*d(ln Z)/dT a very featureless caloric curve is obtained which generally
smoothes too much over structural changes in the system. A new approach for
caloric curves based on the two-dimensional probability distribution P(E,T)
will be discussed.
