Hard disk model: Difference between revisions

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where <math> \Phi_{12}\left(r \right) </math> is the [[intermolecular pair potential]] between two disks at a distance <math>r := |\mathbf{r}_1 - \mathbf{r}_2|</math>, and <math> \sigma </math> is the diameter of the disk. This page treats hard disks in a two-dimensional space, for three dimensions see the page [[hard disks in a three dimensional space]].
where <math> \Phi_{12}\left(r \right) </math> is the [[intermolecular pair potential]] between two disks at a distance <math>r := |\mathbf{r}_1 - \mathbf{r}_2|</math>, and <math> \sigma </math> is the diameter of the disk. This page treats hard disks in a two-dimensional space, for three dimensions see the page [[hard disks in a three dimensional space]].
==Phase transitions==
==Phase transitions==
Despite the apparent simplicity of this model/system, the phase behaviour and the nature of the phase transitions remains an area of active study. In a recent publication by Mak <ref>[http://dx.doi.org/10.1103/PhysRevE.73.065104 C. H. Mak "Large-scale simulations of the two-dimensional melting of hard disks", Physical Review E '''73''' 065104(R) (2006)]</ref>  using over 4 million particles <math>(2048^2)</math> one appears to have the phase diagram isotropic <math>(\rho \leq 0.890)</math> hexatic <math>(\rho > 0.920)</math> solid.
Despite the apparent simplicity of this model/system, the phase behaviour and the nature of the phase transitions remains an area of active study. In a recent publication by Mak <ref>[http://dx.doi.org/10.1103/PhysRevE.73.065104 C. H. Mak "Large-scale simulations of the two-dimensional melting of hard disks", Physical Review E '''73''' 065104(R) (2006)]</ref>  using over 4 million particles <math>(2048^2)</math> one appears to have the phase diagram isotropic <math>(\rho \leq 0.890)</math> hexatic <math>(\rho > 0.920)</math> solid. Similar results have been found using the [[BBGKY hierarchy]] <ref>[http://dx.doi.org/10.1063/1.3491039  Jarosław Piasecki, Piotr Szymczak, and John J. Kozak "Prediction of a structural transition in the hard disk fluid", Journal of Chemical Physics '''133''' 164507 (2010)]</ref>.
 
==Equations of state==
==Equations of state==
:''Main article: [[Equations of state for hard disks]]''
:''Main article: [[Equations of state for hard disks]]''

Revision as of 12:00, 26 October 2010

Hard disks are hard spheres in two dimensions. The hard disk intermolecular pair potential is given by[1] [2]

where is the intermolecular pair potential between two disks at a distance , and is the diameter of the disk. This page treats hard disks in a two-dimensional space, for three dimensions see the page hard disks in a three dimensional space.

Phase transitions

Despite the apparent simplicity of this model/system, the phase behaviour and the nature of the phase transitions remains an area of active study. In a recent publication by Mak [3] using over 4 million particles one appears to have the phase diagram isotropic hexatic solid. Similar results have been found using the BBGKY hierarchy [4].

Equations of state

Main article: Equations of state for hard disks

Virial coefficients

Main article: Hard sphere: virial coefficients

References

Related reading

External links