Nonconcave entropies from generalized canonical ensembles

Costeniuc, Marius; Ellis, Richard S.; Touchette, Hugo

Nonconcave entropies from generalized canonical ensembles

Authors

Costeniuc, Marius

Ellis, Richard S.

Touchette, Hugo

Description

It is well-known that the entropy of the microcanonical ensemble cannot be calculated as the Legendre transform of the canonical free energy when the entropy is nonconcave. To circumvent this problem, a generalization of the canonical ensemble which allows for the calculation of nonconcave entropies was recently proposed. Here, we study the mean-field Curie-Weiss-Potts spin model and show, by direct calculations, that the nonconcave entropy of this model can be obtained by using a specific instance of the generalized canonical ensemble known as the Gaussian ensemble.
5 pages, RevTeX4, 3 figures (best viewed in ps)