An MD Study of SF₆ and Finite Size Annealing

Abstract

The stress-free molecular dynamics method has been used to study the low temperature structure and the plastic-to-crystalline transition of SF₆. When the simulation is performed at low-temperature the structure of the system is monoclinic with space group C2/m which is consistent with neutron diffraction data. A crystal with grain boundaries is obtained when the system is cooled from the plastic phase at a higher temperature. No intermediate phase between the plastic and the monoclinic crystalline phase has been found. This result is in agreement with neutron diffraction experiments but differs from electron diffraction experiments. A tentative explanation of the difference is given.

Key Words:

• Stress-free molecular dynamics
• plastic-crystalline transition
• SF₆
• finite size annealing