[Wien] Question: geometry optimization: constrains

[Peter Blaha]

WIEN2k cannot do this itself.
The way to proceed is to change min_lapw and add a small extra program.
min_lapw extracts the forces and creates case.finM

  grep :FGL $file.scf | tail -$natom | cut -c29-91 >> $file.finM

Here you have to insert a small program which reads the forces, and 
projects out the desired force components and writes them back into 
case.finM
In case.inM use NEW1, this should then move the atoms only in the desired 
plane.

PS: If you have something more "general", I would be interested to add 
this to the WIEN2k distribution. 

> QUESTION: What to do if I would like to constrain positions of an
> atom to movement in a plain [say (111) plane for the primitive
> cubic symmetry], which is NOT parallel to XY, XZ, or YZ planes of
> the global coordinate system? Such an option is required for
> simulation of annealing processes, when an atom moves from one
> local minima to another along a certain path, which needs to be
> determined.


                                      P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
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