Solid--fluid equilibria for hard dumbbells via Monte Carlo simulation

Vega, C; Paras, E P.A.; Monson, P A

doi:10.1063/1.462214

Title: Solid--fluid equilibria for hard dumbbells via Monte Carlo simulation

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Abstract

We present the results of a study of solid--fluid phase equilibria in systems of hard dumbbells for three values of the dumbbell bond length. Monte Carlo simulations were used to calculate the equation of state and Helmholtz free energy. Four orientationally ordered solid phases have been considered---the {alpha}-N{sub 2} structure and three different base centered monoclinic structures formed by the stacking of hexagonally packed layers that allow the dumbbells to achieve their maximum packing density. In addition, a face-centered-cubic (fcc) plastic crystal was studied for the system with the lowest bond length. The three base centered monoclinic structures have thermodynamic properties which are indistinguishable at the level of accuracy in our calculations. For longer bond lengths, the stable solid structure tends to be orientationally ordered base centered monoclinic. However, we also consider the stability of an aperiodic crystal for the case of dumbbells formed from tangent spheres. At lower bond lengths, the system freezes into a fcc plastic crystal which becomes unstable with respect to a base centered monoclinic structure at higher pressure. The transition between these solid phases is apparently first order. The behavior for the lowest bond length considered resembles that of nitrogen at high temperatures. Our resultsmore »« less

Authors:

Vega, C; Paras, E P.A.; Monson, P A ^[1]

Department of Chemical Engineering, University of Massachusetts, Amherst, Massachusetts 01003 (United States)

Publication Date:: Mon Jun 15 00:00:00 EDT 1992

OSTI Identifier:: 7305962

Resource Type:: Journal Article

Journal Name:: Journal of Chemical Physics; (United States)

Additional Journal Information:: Journal Volume: 96:12; Journal ID: ISSN 0021-9606

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; FCC LATTICES; PHASE DIAGRAMS; MONOCLINIC LATTICES; NITROGEN; SOLIDS; BOND LENGTHS; ELONGATION; EQUATIONS OF STATE; EQUILIBRIUM; FLUIDS; FREE ENTHALPY; HARD-SPHERE MODEL; MONTE CARLO METHOD; ORDER PARAMETERS; ORIENTATION; PLASTICITY; PRESSURE DEPENDENCE; SIMULATION; THERMODYNAMIC PROPERTIES; CRYSTAL LATTICES; CRYSTAL STRUCTURE; CUBIC LATTICES; DIAGRAMS; DIMENSIONS; ELEMENTS; ENERGY; EQUATIONS; LENGTH; MECHANICAL PROPERTIES; NONMETALS; PHYSICAL PROPERTIES; 360602* - Other Materials- Structure & Phase Studies; 400201 - Chemical & Physicochemical Properties; 665000 - Physics of Condensed Matter- (1992-)

Citation Formats


                    Vega, C, Paras, E P.A., and Monson, P A. Solid--fluid equilibria for hard dumbbells via Monte Carlo simulation.  United States: N. p., 1992. 
        Web.  doi:10.1063/1.462214.

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                    Vega, C, Paras, E P.A., & Monson, P A. Solid--fluid equilibria for hard dumbbells via Monte Carlo simulation.  United States.  https://doi.org/10.1063/1.462214

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                    Vega, C, Paras, E P.A., and Monson, P A. 1992.  
        "Solid--fluid equilibria for hard dumbbells via Monte Carlo simulation".  United States.  https://doi.org/10.1063/1.462214.

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@article{osti_7305962,

  title        = {Solid--fluid equilibria for hard dumbbells via Monte Carlo simulation},

  author       = {Vega, C and Paras, E P.A. and Monson, P A},

  abstractNote = {We present the results of a study of solid--fluid phase equilibria in systems of hard dumbbells for three values of the dumbbell bond length. Monte Carlo simulations were used to calculate the equation of state and Helmholtz free energy. Four orientationally ordered solid phases have been considered---the {alpha}-N{sub 2} structure and three different base centered monoclinic structures formed by the stacking of hexagonally packed layers that allow the dumbbells to achieve their maximum packing density. In addition, a face-centered-cubic (fcc) plastic crystal was studied for the system with the lowest bond length. The three base centered monoclinic structures have thermodynamic properties which are indistinguishable at the level of accuracy in our calculations. For longer bond lengths, the stable solid structure tends to be orientationally ordered base centered monoclinic. However, we also consider the stability of an aperiodic crystal for the case of dumbbells formed from tangent spheres. At lower bond lengths, the system freezes into a fcc plastic crystal which becomes unstable with respect to a base centered monoclinic structure at higher pressure. The transition between these solid phases is apparently first order. The behavior for the lowest bond length considered resembles that of nitrogen at high temperatures. Our results suggest that the {alpha}-N{sub 2} is not a stable crystal structure for hard dumbbell solids at any bond length, but does appear as a metastable phase in some cases.},

  doi          = {10.1063/1.462214},

  url          = {https://www.osti.gov/biblio/7305962},
  journal      = {Journal of Chemical Physics; (United States)},

  issn         = {0021-9606},

  number       = ,

  volume       = 96:12,

  place        = {United States},

  year         = {Mon Jun 15 00:00:00 EDT 1992},

  month        = {Mon Jun 15 00:00:00 EDT 1992}

}

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