How is the eci calculated

Alloy Theoretic Automated Toolkit (ATAT)
1

Hello, I am interesting in the algorithm about ATAT, and I have some questions

  1. How is the eci calculate?
    I get correlation values by the corrdump command and the energy of the structures generated by maps, I use lsfit, but I can’t get the values which are same as ecis in eci.out.
  2. How maps generates new structures and what’s the meaning of those folders’ name?

Thanks a lot

2

The ECIs you get from a least squares regression of energy on the correlations need to be divided by their multiplicity. See the end of script atat/src/clusterexpand for some guidance.
Also, maps substracts reference state energies while your fit may not. This would affect the empty and point ECI only.

  1. See the paper https://dx.doi.org/10.1361/105497102770331596 for structure generation.
    The numbers have no meaning other than structures with smaller numbers have fewer atoms per cell.