A study of solid and liquid carbon tetrafluoride using the constant pressure molecular dynamics technique

Abstract

The constant pressure molecular dynamics technique originally proposed by Andersen to study fluids and subsequently generalized by Parrinello and Rahman to deal with crystals of arbitrary symmetry has been further extended to treat molecular systems. As a pedagogical example designed to illustrate the utility of this approach, we have investigated the properties of carbon tetrafluoride in its condensed phases using an intermolecular potential based upon atom–atom interactions. In particular, we have explored the effect of changes in temperature and pressure on the orientationally ordered low temperature monoclinic solid. As in the real crystal, isobaric heating to sufficiently high temperature causes the ordered phase to transform spontaneously to a noncubic orientationally disordered phase. The properties of this disordered phase are also examined along with those of the liquid. The atom–atom potential appears to correlate a wide range of experimental data. The possible role of the electrostatic octopole–octopole interactions is also discussed briefly.

Keywords

Affiliated Institutions

• National Research Council Canada CA

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