Effect of octupole–octupole interactions on the thermodynamic stability of the low-pressure crystalline state of SnI4 molecular crystals

A recent experimental investigation into the low-pressure crystalline state of an SnI4 molecular crystal under high pressure has revealed that the melting points predicted from molecular dynamics simulations were too high. The short-range octupole–octupole intermolecular interaction, which plays an important role at high pressures, was newly introduced to the model to accommodate this effect. These interactions do indeed destabilize the crystalline state. However, the degree of destabilization was too small to quantitatively reproduce the experimental melting points. A possible origin of the discrepancy is discussed.