“…In the case of pseudospherical-shaped molecules, the orientational order is lost first, giving a phase where molecules are able to reorient on their lattice sites, a phase commonly known as plastic phase, a term which is also used to describe the high-temperature phase existing just before the liquid state . In spite of the similarity in size and intermolecular interactions, the polymorphic behavior within the realm of MHM compounds at normal pressure (i.e., in equilibrium with its vapor pressure), as well as at high pressure, is known to be quite different, a fingerprint that small differences of size and intermolecular interactions finely tune the thermodynamic functions accounting for the stability of the phases. − ,− ,− ,, The stability of the phases can be revealed not only by means of the study of pure compounds, as a function of temperature and pressure, but also by the determination of the phase diagram between two homologous compounds. ,,,− With the last procedure, the formation of mixed crystals provides information on the thermodynamic mixing properties, thus on the interactions between their molecular units and, in some cases, on the intrinsic polymorphic behavior of the pure compounds. , …”