Potts model: Difference between revisions

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The '''Potts model''' was proposed by Renfrey B. Potts in 1952 (Ref. 1). The Potts model is a generalisation of the [[Ising Models | Ising model]] to more than two components. For a general discussion on Potts models see Refs. 2 and 3.
The '''Potts model''' was proposed by Renfrey B. Potts in 1952 (Ref. 1). The Potts model is a generalisation of the [[Ising Models | Ising model]] to more than two components.
 
For a general discussion on Potts models see Ref.2.
 
In practice one has a lattice system. The sites of the lattice can be occupied by
In practice one has a lattice system. The sites of the lattice can be occupied by
particles of different '''species''', <math> S=1,2, \cdots, q </math>.
particles of different ''species'', <math> S=1,2, \cdots, q </math>.


The energy of the system, <math> E </math>,  is defined as:
The energy of the system, <math> E </math>,  is defined as:


:<math> E =  - K \sum_{<ij>} \delta (S_i,S_j) </math>
:<math> E =  - K \sum_{ \langle ij \rangle } \delta (S_i,S_j) </math>
where <math> K </math> is the coupling constant, <math> <ij> </math> indicates
where <math> K </math> is the coupling constant, <math> \langle ij \rangle </math> indicates
that the sum is done exclusively over pairs of nearest neighbor sites,  and <math> \delta(S_i,S_j) </math> is the [[Kronecker delta|Kronecker delta]].
that the sum is performed exclusively over pairs of nearest neighbour sites,  and <math> \delta(S_i,S_j) </math> is the [[Kronecker delta|Kronecker delta]].
 
Note that the particular case <math> q=2 </math> is equivalent to the [[Ising Models | Ising model]]
The particular case <math> q=2 </math> is equivalent to the [[Ising Models | Ising model]]
==See also==
==See also==
*[[Ashkin-Teller model]]
*[[Ashkin-Teller model]]

Revision as of 16:38, 4 July 2008

The Potts model was proposed by Renfrey B. Potts in 1952 (Ref. 1). The Potts model is a generalisation of the Ising model to more than two components. For a general discussion on Potts models see Refs. 2 and 3. In practice one has a lattice system. The sites of the lattice can be occupied by particles of different species, Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle S=1,2, \cdots, q } .

The energy of the system, Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle E } , is defined as:

Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle E = - K \sum_{ \langle ij \rangle } \delta (S_i,S_j) }

where is the coupling constant, Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \langle ij \rangle } indicates that the sum is performed exclusively over pairs of nearest neighbour sites, and Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \delta(S_i,S_j) } is the Kronecker delta. Note that the particular case Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle q=2 } is equivalent to the Ising model

See also

References

  1. Renfrey B. Potts "Some generalized order-disorder transformations", Proceedings of the Cambridge Philosophical Society 48 pp. 106−109 (1952)
  2. F. Y. Wu "The Potts model", Reviews of Modern Physics 54 pp. 235-268 (1982)
  3. F. Y. Wu "Erratum: The Potts model", Reviews of Modern Physics 55 p. 315 (1983)