Molecular Crystal Calculation Prospects for Structural Phase Transitions

To establish the theory of soft crystals, computational chemistry must be applied to analyze the structural phase transitions of molecular crystals and develop new methodologies. The accuracy of first-principles calculations for molecular crystals has rapidly improved over the last decade with the contribution of the Cambridge Crystallographic Data Centre blind test, which predicts the crystal structure from the structural formula. However, it is often difficult to apply first-principles calculations to large molecular crystals, such as typical soft crystals, because of the computational cost. In this chapter, we review the applicability of crystal force field calculations as an alternative method for theoretically analyzing molecular crystals. We also introduce some examples of our previous collaborations and discuss the promising methodologies to elucidate the soft crystal phenomena.