[Wien] Symmetry changed during geometry optimization

Peter Blaha pblaha at zeus.theochem.tuwien.ac.at
Thu Mar 17 17:12:55 CET 2005

Your problem seems to be more complex than usual. I do not think it is 
related to any "rounding" problems in any versions ....

Checking your struct files I see that
a) you neglect the suggestion of sgroup to describe the structure as 
rhombohedral lattice. Something like this is potentially dangerous, 
however, I must admit that I would have done the same in this case and it 
should be a valid struct file.

b) your symmetries are quite simple, you just have 3 "types", MULT=1 
positions (for this only "ONE" force exists, and the changes must be 
dx,dx,dx (and they are as far as I can see).
MULT=6 has no symmetry left and 3 independen forces. As far as I can see, 
mini changed all equivalent atoms in the proper way.
MULT=3 with 2 independend forces and the positions should shift according 
to dx,dx,dz (or permutations). Again this is obeyed for ALL positions 
except atom=6 ! There the shift is dx,-dx,dz ! and this I don't quite 
understand yet.

When you remove atom6 from the new struct file, symmetry should be ok.

To get further information could you please send me the forces part of 
your scf file (or better, the full last scf iteration) (to my private 
I'm wondering how the forces look like and what mini will do.

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/

More information about the Wien mailing list