Universality classes: Difference between revisions
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(→Ising) |
(→Ising) |
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<math> | <math> | ||
H=\ | H=\sum_{<i,j>}S_i S_j | ||
</math> | </math> | ||
where | where <math>S_i=\pm 1<math> and the summation runs over the lattice sites. | ||
The order parameter is | The order parameter is | ||
<math> | |||
m=\sum_i S_i | m=\sum_i S_i | ||
</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> | |||
\alpha=0 | \alpha=0 | ||
</math> | |||
(In fact, the specific hear diverges logarithmically with the critical temperature) | (In fact, the specific hear diverges logarithmically with the critical temperature) | ||
<math> | |||
\beta=\frac{1}{8} | \beta=\frac{1}{8} | ||
</math> | |||
<math> | |||
\gamma=\frac{7}{4} | \gamma=\frac{7}{4} | ||
</math> | |||
<math> | |||
\delta=15 | \delta=15 | ||
</math> | |||
==Local linear interface== | ==Local linear interface== | ||
Revision as of 13:11, 20 July 2011
| 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
In two dimensions, Onsager obtained the exact solution in the absence of a external field, and the critical exponents are (In fact, the specific hear diverges logarithmically with the critical temperature)