Find ground state for binary alloy with specific composition

Alloy Theoretic Automated Toolkit (ATAT)
1

Dear all,

I’m new to this ATAT tool, just reading ATAT manual. My system is two component alloy (A and B) and I want find the most stable configuration of AmBn (bulk) with specific composition (for example, A13B4). My system is not simple fcc, bcc or hcp. It’s more like two bcc structure merged.

My first question is, can I find most stable configuration of A13B4 using ATAT? I can calculate the energy of specific configurations using VASP, but I cannot figure out all the possible configurations… That’s why I thing about cluster expansion and ATAT, but not sure if ATAT can do this?

My second question is, if I can use ATAT to calculate my system, can I input my structure information in lat.in file, since ATAT works for fcc, bcc and hcp most?

Your help will be really appreciated!

Thank you!

Haoran He

2

It is not a good idea to minimize the energy while looking only at one composition because the "ground state" at that composition could be a phase-separated mixture of multiple phases that bracket that composition. However, there is a way to achieve what you want.

When you run maps, you can specify a composition range with the -c0=… and -c1=… options. Then maps will try to make sure that the ground states are correct in that region and will thus generate structures in that range. Note that it will also generate structure outside of that range if it finds one that might be part of a phase-separated mixture that involves a phase within that composition region.

Finally, yes, ATAT can handle beyond bcc,fcc, hcp. Just enter the appropriate lat.in file.