Although these studies have provided novel and invaluable information regarding the nature of DPT, we note that most of these studies are primarily cases where the effect of crystal environment have been either ignored by taking single molecule and dimer or partially incorporated through a chain of molecules. However, a complete description of crystal field, much like solvent effects, 41 is necessary. One of the discernible effect of crystal field is the non-degeneracy of the tautomers caused due to the induced asymmetry of the potential energy surface. The non-degeneracy manifests by modifying the rates of tautomerization which are critical in systems where the proton transfer processes are controlled by external stimuli such as electric field, light, heat, and stress. These fascinating reports prompted us to undertake a theoretical study on the nature of DPT. Therefore, in this work we investigate DPT in molecular crystals of terephthalic acid (TPA). The choice provides a more realistic and less complicated system to understand the nature of DPT and how it is modulated by the environment. TPA is also used as a commercial precursor in the polymer industry. Moreover, the molecules of TPA are used as ligands for synthesizing metal-organic frameworks and supramoleculer complexes catering to a wide range of applications. More recently, Karothu and coworkers 48 observed that the application of thermal/mechanical stimulus on the crystals of TPA results in a polymorphic phase transition. This behaviour is referred to as thermosalient/mechanosalinet effect and has important applications in the design of transducers.