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**Up:** Spatial Inhomogeneity. Interfaces
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In the previous lecture we obtained for Ising lattice:

(1) |

and

Consider a simple cubic lattice. Each spin in the layer *l* has *z*=6
neighbors:

- One neighbor in the layer
*l*+1 - One neighbor in the layer
*l*-1 -
*z*-2 neighbors in the layer*l*

Changes to equation (1): substitute *N* by sum over
layers. Then:

- 1.
- The first term describes mean interaction of a given spin with
*z*neighbors. Substitute*zM*for^{2} - 2.
- The second term describes molecular field acting on a given spin
(in the layer
*l*). Substitute*zM*by

**Assumption:**- Magnetization
*M*(*l*) changes at distances much larger than the lattice size*a*_{0}

We see that in SCF *A* can be represented as

© 1997

Thu Oct 16 20:58:44 EDT 1997