[Wien] "X-FORCE for atom 1 is not zero as required by symmetry"

[Peter Blaha]

> 1) I am using version 13.1. Still, min_lapw has changed the space group
> number from 14 to 4, which I only noticed after Gerhard had pointed this
> out. The regular scf cycle was done with the correct space group in
> .struct and produced "X-FORCE for atom 1 is not zero as required by
> symmetry".

The spacegroup-label in the struct file is NOT used at all, except in the
structgenerator of w2web.
In other words, you can put there anything and as long as you do not load
such a struct file into structgen at w2web and press SAVE/ACCEPT CHANGES, there
is no effect-

Nevertheless, I'll modify the structgenerator, such that it writes a blank
in between #of atoms and SG number, as this is very confusing.

> 3) If possible, I'd like to keep this space group or, at least, the unit
> cell dimensions for further analysis.
>
> So, can I conclude that it is not possible to optimize the position of the
> first atom using this space group/unit cell dimensions because of not
> accepting the space group suggested by sgroup? Perhaps, I should try
> reducing the symmetry to P1...

It should be possible. I did not check it very carefully, but to my understanding
you do NOT need to follow the suggestion of sgroup and can keep the unit cell as
desired. (I still do not know who wrote these local rotation matrices into case.struct ???)

Please transfer the struct file to a new directory.

Put the number of symmetry operations to ZERO in case.struct
(use an editor, not "structgen" to avoid any problems with the SG-label).

Then reinitialize again and run mini again.


-- 
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Peter Blaha
Inst. Materials Chemistry, TU Vienna
Getreidemarkt 9, A-1060 Vienna, Austria
Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pblaha at theochem.tuwien.ac.at
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