I often use selective dynamics to do structure optimization in VASP, but I am not sure how to do it when using ASE, it seems I could use the constraint class to tell ASE what I want to do.
My question is:
When I use the constraint
class, does ASE generate the POSCAR that includes the selective dynamics
parameter? Or it is like the case of optimizer, ASE could just use VASP as a calculator, and set the constraint outside the loop of VASP calculation?
1 Answer
The FixAtoms
constraint will be turned into the selective dynamics tags as "F F F". ASE will also convert selective dynamics to this constraint when reading.
I think the FixedPlane
and FixedLine
could in theory also work, but I am not sure they do since they support directions not aligned with the X, Y, and Z axis. If you need this and it doesn't work (just give it a try), you might ask on the ASE Matrix chat to see if someone is willing to add it for you or tell you how to change it yourself.