Difference between revisions of "Hard tetrahedron model"

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(Truncated tetrahedra)
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[[Image:tetrahedron.png|thumb|right]]
 
[[Image:tetrahedron.png|thumb|right]]
The '''hard tetrahedron model'''. Such a structure has been put forward as a potential model for [[water]]<ref>[http://dx.doi.org/10.1080/00268979500100281 Jiri Kolafa and Ivo Nezbeda "The hard tetrahedron fluid: a model for the structure of water?", Molecular Physics '''84''' pp. 421-434 (1995)]</ref>.  
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The '''hard tetrahedron model''' is a subset of [[hard polyhedra model]] that has been put forward as a potential model for [[water]]<ref>[http://dx.doi.org/10.1080/00268979500100281 Jiri Kolafa and Ivo Nezbeda "The hard tetrahedron fluid: a model for the structure of water?", Molecular Physics '''84''' pp. 421-434 (1995)]</ref>.  
 
==Maximum packing fraction==
 
==Maximum packing fraction==
 
It has recently been shown that regular tetrahedra are able to achieve packing fractions as high as <math>\phi=0.8503</math><ref>[http://dx.doi.org/10.1038/nature08641 Amir Haji-Akbari, Michael Engel, Aaron S. Keys, Xiaoyu Zheng, Rolfe G. Petschek, Peter Palffy-Muhoray  and  Sharon C. Glotzer "Disordered, quasicrystalline and crystalline phases of densely packed tetrahedra", Nature '''462''' pp. 773-777 (2009)]</ref> (the [[hard sphere model |hard sphere]] packing fraction is  <math>\pi/(3 \sqrt{2}) \approx 74.048%</math> <ref>[http://dx.doi.org/10.1038/26609 Neil J. A. Sloane "Kepler's conjecture confirmed", Nature '''395''' pp. 435-436 (1998)]</ref>). This is in stark contrast to work as recent as in 2006, where it was suggested that the "...regular tetrahedron might even be the convex body having the smallest possible packing density"<ref>[http://dx.doi.org/10.1073/pnas.0601389103 J. H. Conway and S. Torquato "Packing, tiling, and covering with tetrahedra", Proceedings of the National Academy of Sciences of the United States of America '''103''' 10612-10617 (2006)]</ref>.
 
It has recently been shown that regular tetrahedra are able to achieve packing fractions as high as <math>\phi=0.8503</math><ref>[http://dx.doi.org/10.1038/nature08641 Amir Haji-Akbari, Michael Engel, Aaron S. Keys, Xiaoyu Zheng, Rolfe G. Petschek, Peter Palffy-Muhoray  and  Sharon C. Glotzer "Disordered, quasicrystalline and crystalline phases of densely packed tetrahedra", Nature '''462''' pp. 773-777 (2009)]</ref> (the [[hard sphere model |hard sphere]] packing fraction is  <math>\pi/(3 \sqrt{2}) \approx 74.048%</math> <ref>[http://dx.doi.org/10.1038/26609 Neil J. A. Sloane "Kepler's conjecture confirmed", Nature '''395''' pp. 435-436 (1998)]</ref>). This is in stark contrast to work as recent as in 2006, where it was suggested that the "...regular tetrahedron might even be the convex body having the smallest possible packing density"<ref>[http://dx.doi.org/10.1073/pnas.0601389103 J. H. Conway and S. Torquato "Packing, tiling, and covering with tetrahedra", Proceedings of the National Academy of Sciences of the United States of America '''103''' 10612-10617 (2006)]</ref>.

Revision as of 04:00, 4 December 2012

Tetrahedron.png

The hard tetrahedron model is a subset of hard polyhedra model that has been put forward as a potential model for water[1].

Maximum packing fraction

It has recently been shown that regular tetrahedra are able to achieve packing fractions as high as \phi=0.8503[2] (the hard sphere packing fraction is \pi/(3 \sqrt{2}) \approx 74.048% [3]). This is in stark contrast to work as recent as in 2006, where it was suggested that the "...regular tetrahedron might even be the convex body having the smallest possible packing density"[4].

Phase diagram

[5]

Truncated tetrahedra

Dimers composed of Archimedean truncated tetrahedra are able to achieve packing fractions as high as \phi= 207/208 \approx 0.9951923 [6][7] while a non-regular truncated tetrahedra can completely tile space [8].

References

Related reading