# Constant for different types of lattices

1. ### LagrangeEuler

360
##C=\frac{1}{N}\sum_{\vec{k}} \frac{J(0)}{J(0)-J(\vec{k})} ##
##J(\vec{k})## is exchange integral in ##\vec{k}## space. What is the name of this constant and where I can find more about it?

For simple cubic lattice
##C_{SC}=1.516##

Last edited: Jan 19, 2014
2. ### M Quack

852
Can you provide a bit more context?

Exchange integrals usually depend on details of the band structure, so I am surprised that you can get a universal constant for all simple cubic lattices irrespective of lattice constant, atomic flavor etc.

J(0) would favor ferromagnetism

J(k) with k != 0 would favor antiferromagnetism with a modulation wave vector k.

3. ### LagrangeEuler

360
See this paper.

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360
Or here.

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