A generalized van der Waals theory of solid-fluid equilibria for non-spherical molecules
作者:
E.P.A. Paras,
C. Vega,
P.A. Monson,
期刊:
Molecular Physics
(Taylor Available online 1993)
卷期:
Volume 79,
issue 5
页码: 1063-1072
ISSN:0026-8976
年代: 1993
DOI:10.1080/00268979300101831
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
By making use of recently obtained theoretical and Monte Carlo simulation results for solid state thermodynamics and solid-fluid equilibria for systems of hard dumbbells a generalized van der Waals theory of solid-fluid equilibria has been formulated. The theory predicts how the temperature dependence of the solid-liquid (and vapour-liquid) equilibrium is influenced by non-spherical molecular shape for diatomic molecules. Two regimes of behaviour are identified, depending on whether the underlying hard dumbbell reference system freezes into a plastic crystal or an orientationally ordered crystal. The theory correctly predicts a decrease in the triple point temperature and density change on freezing between spherical molecules, such as argon, and slightly non-spherical molecules which freeze into plastic crystal phases such as nitrogen. An extension of the theory which includes a simplified treatment of the influence of quadrupolar interactions provides a plausible explanation for the relatively high reduced triple point temperature of carbon dioxide.
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