  Polymorphism, which describes the occurrence of different lattice structures
in a crystalline material, is a critical phenomenon in material science and
condensed matter physics. It has emerged as a major focus for industry and
regulatory agencies respectively. Thermomicroscopy, infrared spectroscopy and
thermal analysis, especially differential scanning calorimetry (DSC) is used to
characterize polymorphism to provide a powerful to isolate and identify of
crystalline modification. Enantiotropic and monotropic with reversible
endothermic and irreversible exothermic phase transition is representative
classifications of polymorphism. Recently, Dirac metamaterial based on pyrene
derivatives is attracting great attention. It succeeded in forming a periodic
and regular structure using the unique {\pi}-{\pi} interaction of the pyrene
derivative, namely HYLION-12. The phase transition between modifications is not
classified into the existing polymorphism system. Here, we propose a new kind
of polymorphism by identifying and analyzing thermodynamic functions such as
heat capacity, enthalpy, entropy and, Gibbs free energy between modifications
from DSC. This not only allows us to better understand the formation of Dirac
materials at the molecular level, but also to think about the condition for new
types of polymorphism.
