Multicomponent cluster function.

Alloy Theoretic Automated Toolkit (ATAT)
1

Hi,
I was reading Multicomponent multisublattice alloys, nonconfigurational entropy and other
additions to the Alloy Theoretic Automated Toolkit, 2009

And I did not really get how the correlation function is chosen for a ternary system. How are the values for sigma_i chosen? It is zero if site i not belongs to the cluster and a value between 1 and M_i-1 depending on what exactly?

2

I think I have figured it out. It seems that you don’t make a choice of which cluster functions to add, you add all possible ones. For a ternary, only considering singlets and pairs and you have,say, 10 unique distances you will have to fit 32 parameters?

3

You are correct. (Although the exact number of resulting clusters depends on the symmetry of the system.)