Universality classes: Difference between revisions

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m (→‎Ising: Added some internal links)
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==Directed percolation==
==Directed percolation==
==Ising==
==Ising==
The Hamiltonian of the Ising model is  
The [[Hamiltonian]] of the [[Ising model]] is  


<math>
<math>
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where <math>S_i=\pm 1</math> and the summation runs over the lattice sites.
where <math>S_i=\pm 1</math> and the summation runs over the lattice sites.


The order parameter is  
The [[Order parameters | order parameter]] is  
<math>
<math>
m=\sum_i S_i
m=\sum_i S_i
</math>
</math>


In two dimensions, Onsager obtained the exact solution in the absence of a external field, and the critical exponents are
In two dimensions, Onsager obtained the exact solution in the absence of a external field, and the [[critical exponents]] are
<math>
<math>
\alpha=0
\alpha=0
</math>
</math>
(In fact, the specific hear diverges logarithmically with the critical temperature)
(In fact, the [[Heat capacity |specific heat]] diverges logarithmically with the [[Critical points |critical temperature]])


<math>
<math>

Revision as of 14:46, 20 July 2011

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name
3-state Potts
Ashkin-Teller
Chiral
Directed percolation
Ising
Local linear interface
Mean-field
Molecular beam epitaxy
Random-field

3-state Potts

Ashkin-Teller

Chiral

Directed percolation

Ising

The Hamiltonian of the Ising model is


where and the summation runs over the lattice sites.

The order parameter is

In two dimensions, Onsager obtained the exact solution in the absence of a external field, and the critical exponents are (In fact, the specific heat diverges logarithmically with the critical temperature)

Local linear interface

Mean-field

Molecular beam epitaxy

See also

Random-field