Hard spherocylinders: Difference between revisions

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The '''hard spherocylinder''' model consists of an  impenetrable cylinder, capped at both ends  
The '''hard spherocylinder''' model consists of an  impenetrable cylinder, capped at both ends  
by hemispheres whose diameters are the same as the diameter of the cylinder. The hard spherocylinder model
by hemispheres whose diameters are the same as the diameter of the cylinder. The hard spherocylinder model
has been studied extensively because of its propensity to form both [[Nematic phase | nematic]] and [[Smectic phases | smectic]] [[Liquid crystals | liquid crystalline]] phases <ref>[http://dx.doi.org/10.1038/332822a0 D. Frenkel, H. N. W. Lekkerkerker and A. Stroobants "Thermodynamic stability of a smectic phase in a system of hard rods", Nature '''332''' p. 822 (1988)]</ref> as well as forming a [[Plastic crystals | plastic crystal]] phase for short <math>L</math> <ref>[http://dx.doi.org/10.1063/1.474626 C. Vega and P. A. Monson "Plastic crystal phases of hard dumbbells and hard spherocylinders", Journal of Chemical Physics '''107''' pp. 2696-2697 (1997)]</ref> . One of the first studies of  hard spherocylinders was undertaken by Cotter and Martire <ref>[http://dx.doi.org/10.1063/1.1673232  Martha A. Cotter and Daniel E. Martire "Statistical Mechanics of Rodlike Particles. II. A Scaled Particle Investigation of the Aligned to Isotropic Transition in a Fluid of Rigid Spherocylinders", Journal of Chemical Physics  '''52''' pp. 1909-1919 (1970)]</ref> using [[scaled-particle theory]], and one of the first simulations was in the classic work of Jacques Vieillard-Baron <ref>[http://dx.doi.org/10.1080/00268977400102161 Jacques Vieillard-Baron  "The equation of state of a system of hard spherocylinders", Molecular Physics '''28''' pp. 809-818 (1974)]</ref>. In the limit of zero diameter the hard spherocylinder becomes a line segment, often known as the [[3-dimensional hard rods |hard rod model]], and in the limit <math>L=0</math> one has the [[hard sphere model]].
has been studied extensively because of its propensity to form both [[Nematic phase | nematic]] and [[Smectic phases | smectic]] [[Liquid crystals | liquid crystalline]] phases <ref>[http://dx.doi.org/10.1038/332822a0 D. Frenkel, H. N. W. Lekkerkerker and A. Stroobants "Thermodynamic stability of a smectic phase in a system of hard rods", Nature '''332''' p. 822 (1988)]</ref> as well as forming a [[Plastic crystals | plastic crystal]] phase for short <math>L</math> <ref>[http://dx.doi.org/10.1063/1.474626 C. Vega and P. A. Monson "Plastic crystal phases of hard dumbbells and hard spherocylinders", Journal of Chemical Physics '''107''' pp. 2696-2697 (1997)]</ref> . One of the first studies of  hard spherocylinders was undertaken by Cotter and Martire <ref>[http://dx.doi.org/10.1063/1.1673232  Martha A. Cotter and Daniel E. Martire "Statistical Mechanics of Rodlike Particles. II. A Scaled Particle Investigation of the Aligned to Isotropic Transition in a Fluid of Rigid Spherocylinders", Journal of Chemical Physics  '''52''' pp. 1909-1919 (1970)]</ref> using [[scaled-particle theory]], and one of the first simulations was in the classic work of Jacques Vieillard-Baron <ref>[http://dx.doi.org/10.1080/00268977400102161 Jacques Vieillard-Baron  "The equation of state of a system of hard spherocylinders", Molecular Physics '''28''' pp. 809-818 (1974)]</ref>. In the limit of zero diameter the hard spherocylinder becomes a line segment, often known as the [[3-dimensional hard rods |hard rod model]], and in the limit <math>L=0</math> one has the [[hard sphere model]]. A closely related model is that of the [[Oblate hard spherocylinders | oblate hard spherocylinder]].
==Volume==
==Volume==
The molecular volume of the spherocylinder  is given by  
The molecular volume of the spherocylinder  is given by  

Revision as of 12:22, 2 March 2011

The hard spherocylinder model consists of an impenetrable cylinder, capped at both ends by hemispheres whose diameters are the same as the diameter of the cylinder. The hard spherocylinder model has been studied extensively because of its propensity to form both nematic and smectic liquid crystalline phases [1] as well as forming a plastic crystal phase for short [2] . One of the first studies of hard spherocylinders was undertaken by Cotter and Martire [3] using scaled-particle theory, and one of the first simulations was in the classic work of Jacques Vieillard-Baron [4]. In the limit of zero diameter the hard spherocylinder becomes a line segment, often known as the hard rod model, and in the limit one has the hard sphere model. A closely related model is that of the oblate hard spherocylinder.

Volume

The molecular volume of the spherocylinder is given by

where is the length of the cylindrical part of the spherocylinder and is the diameter.

Minimum distance

The minimum distance between two spherocylinders can be calculated using an algorithm published by Vega and Lago [5]. The source code can be found here. Such an algorithm is essential in, for example, a Monte Carlo simulation, in order to check for overlaps between two sites.

Virial coefficients

Main article: Hard spherocylinders: virial coefficients

Phase diagram

Main aritcle: Phase diagram of the hard spherocylinder model

See also

References

Related reading