Gibbs free energy, $G$, for a crystalline solid material could be described as: \begin{equation} G\: =\: H_{T=0}\: +\: H_{T>0}\: +\: \text{ZPE}\: -\: T\cdot S, \end{equation} Where $H$ is enthalpy, ZPE is the zero-point energy and S is entropy (all kinds).
Solids (condensed matter might be a better term) are highly incompressible, so their internal energy computed with either empirical potentials or otherwise can be considered equal to their enthalpy. That takes care of the $H_{T=0}$ term. What about the rest? Can each of them be included in a Thermocalc phase transition study?
I haven't explored Thermocalc enough (blame it on VASP!). As far as I know, we make Gibbs free energy equations for a material at various temperature ranges and dump those in a .tdb (database) file. If these other terms are accounted for, please help me understand how, code and theory-wise.