intermolecular interactions Density Functional Theory 1 Dimerization 1 Molecular Conformation 1 Phase Transition 1 Pressure 1 conformation 1 crystal structure 1 density functional theory 1 dimerization 1 high pressure 1 hirshfeld surfaces 1 organic radicals 1 phase transition 1 phase transitions 1 pressure 1 thiourea 1 π-stacking 1