Editing Anisotropic particles with tetrahedral symmetry

[[Image:patchy_4.png|thumb|right| Artists impression of a tetrahedral patchy particle]]
'''Anisotropic particles with tetrahedral symmetry'''
==Kern and Frenkel model==
===Phase diagram===
The [[Phase diagrams |phase diagram]] of the tetrahedral [[Kern and Frenkel patchy model | Kern and Frenkel ]] [[patchy particles | patchy model]] exhibits the following solid phases<ref>[http://dx.doi.org/10.1021/jp9081905 Flavio Romano, Eduardo Sanz and Francesco Sciortino  "Role of the Range in  the Fluid−Crystal Coexistence for a Patchy Particle Model", Journal  of Physical Chemistry B '''113''' pp. 15133–15136 (2009)]</ref><ref>[http://dx.doi.org/10.1063/1.3393777 Flavio Romano, Eduardo Sanz and Francesco Sciortino "Phase diagram of a tetrahedral patchy particle model for different interaction ranges", Journal of Chemical Physics '''132''' 184501 (2010)]</ref>:
[[Building up a diamond lattice |diamond crystal]] (DC),
[[Building up a body centered cubic lattice | body centred cubic]] (BCC) and [[Building up a face centered cubic lattice |face centred cubic]] (FCC). The gas-liquid [[critical points | critical point]] becomes metastable with respect
to the diamond crystal when the range of the interaction becomes short (roughly less than 15% of the 
diameter).  

:[[Image:romanojpcb09.gif]]

In contrast to isotropic models, the critical point becomes only weakly metastable  with respect to the solid as the interaction range 
narrows (from left to right in the figure).

===Crystallization===

Tetrahedral Kern-Frenkel patchy particles crystallise spontaneously into open tetrahedral networks for narrow patches (solid angle < 30). The interaction range does not play an important role in crystallisation <ref>[http://dx.doi.org/10.1063/1.3578182 Flavio Romano, Eduardo Sanz, and Francesco Sciortino "Crystallization of tetrahedral patchy particles in silico", Journal of Chemical Physics '''134''' 174502 (2011)]</ref>

[[Image:fig5.jpg]]

Interaction range, <math>\delta</math>, versus patch angular width. 
Diamonds correspond to crystallising and circles to glass–forming models. 
The point studied in Ref. <ref>[http://dx.doi.org/10.1063/1.3578182 Zhenli Zhang, Aaron S. Keys, Ting Chen, and Sharon C. Glotzer "Self-Assembly of Patchy Particles into Diamond Structures through Molecular Mimicry", Langmuir '''21''' 11547 (2005)]</ref> is included.

When the patches in this model are made even wider (while still enforcing the limit of a single bond per patch), the diamond phase becomes metastable with respect to a liquid phase, which is stable even in the zero-temperature limit <ref>[http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys2693.html Frank Smallenburg and Francesco Sciortino "Liquids more stable than crystals in particles with limited valence and flexible bonds", Nature Physics '''9''' 554 (2013)]</ref>.

==Modulated patchy Lennard-Jones model==
The solid phases of the [[modulated patchy Lennard-Jones model]] has also been studied <ref>[http://dx.doi.org/10.1063/1.3454907  Eva G. Noya, Carlos Vega, Jonathan P. K. Doye, and Ard A. Louis "The stability of a crystal with diamond structure for patchy particles with tetrahedral symmetry", Journal of Chemical Physics '''132''' 234511 (2010)]</ref>
==Lattice model==
<ref>[http://dx.doi.org/10.1080/00268976.2010.523521 N. G. Almarza and E. G. Noya "Phase transitions of a lattice model for patchy particles with tetrahedral symmetry", Molecular Physics '''109''' pp. 65-74 (2011)]</ref>

==See also==
*[[PMW]] (primitive model for [[water]])

== References ==
<references/>
;Related reading
*[http://dx.doi.org/10.1063/1.3582904 G. Munaó, D. Costa, F. Sciortino, and C. Caccamo "Simulation and theory of a model for tetrahedral colloidal particles", Journal of Chemical Physics '''134''' 194502 (2011)]
[[category: models]]