Running emc2

Alloy Theoretic Automated Toolkit (ATAT)
1

I have completed running a cluster expansion using ATAT on an Fe-C crystal structure and have found 7 ground states and 75 total structures. I am now trying to calculate the free energy surface (based on wt%C) from 300K to 500K, but I am have trouble trying to figure out how to start the the process in emc2. I’ve used the command:

emc2 -gs=5 -T0=300 -T1=500 -dT=20 -k=8.617e-5 -dx=1e-3 -er=60 -innerT -cm -o=mc5.out

but this has not worked so far. Any help will be greatly appreciated.

2

Can you please provide details as to how this failed?

3

I’m not sure if it is failing, but I have let it run for days and I’m not getting any output. I’ve run the example problems and they seem to run fine, so I am fairly certain that I am not calling the right options in emc2. For example, which -gs should I choose, 0 … 6 (i.e., there 7 identified ground states)? Or should I try running emc2 for each -gs value? Do I need to specify the concentration, if so how? Ultimately, I need to calculate the Gibbs free energy surface from 300K to 500K, from 0wt%C to ~17wt%C (i.e., this correspond the ATAT cluster expansion 0C-1C), and I cannot figure out how to structure the emc2 command to calculate this. Thank you.

4

Suggestions:

  1. I see you are using -cm (canonical mode). If you do that and gs=5 is a pure structure (all sites occupied in the same way), then nothing can happen. It is more convenient to use the default grandcanonical mode if you will be scanning different compositions anyways.
  2. To see what is happening, try using -n=… -eq=… instead of -dx to force to code to report an output after a given amount of steps rather than a given precision.