MOLECULAR-DYNAMICS SIMULATION STUDY OF THE BEHAVIOR OF MOLECULAR-CRYSTAL TIN TETRAIODIDE UNDER HYDROSTATIC-PRESSURE

Isothermal-isobaric molecular dynamics simulations of molecular crysta l SnI4 are carried out based on a model consisting of rigid tetrahedra l molecules interacting via van der Waals forces. The hehavior of the crystal upon an increase in pressure is satisfactorily reproduced on b oth microscopic and macroscopic scales in the pressure regime in which the low-pressure phase is stable. In particular the compression curve obtained is in excellent agreement with the experimentally determined one. Upon further increase in pressure, however. no symmetry change i s detected in the present simulations over the pressure regime in whic h the phase transformation and the subsequent solid state amorphizatio n are experimentally found to take place.