[Pw_forum] "Not orthogonal operation" error in vc-relax optimization

mohnish pandey mohnish.iitk at gmail.com
Tue May 24 12:12:39 CEST 2011

Dear Seyed!
  The relaxation of cell is breaking the symmetry, this error message shows
that. For example, if you use surface unit cell as hexagonal and try to
relax the 'x' and 'y' direction of the cell, then it will give the error
message because the cell vector is not orthogonal and the direction of
relaxation of your cell is is independent in 'x' and 'y' direction. So if
you want to get to rid of this error message then the direction of
relaxation should be in the direction of unit cell vector.  The relaxation
process should not break the symmetry of the system. Hope it helps. Feel
free to ask further if you have any doubts.

On Tue, May 24, 2011 at 11:35 AM, Seyed Mojtaba Rezaei Sani <
s.m.rezaeisani at gmail.com> wrote:

> Dear all
> My vc-relax opt, although I set cell dynamics='damp-w',ends with this
> error :
> >  from checkallsym : error #         2
> >  not orthogonal operation
> Is there any suggestion for solving that?
> (If anyone thinks about using nonsymmetric cell, I will send my input file
> and will be grateful to learn how it can be)
> Thanks
> --
> ==========================================
>  Seyed Mojtaba Rezaei Sani
> Computational Condensed Matter Research Lab
> Physics Department, Isfahan University of Technology
> 84156-83111 Isfahan, Iran
> Tel Lab: +98 311 391 3731
> s.rezaeisani at ph.iut.ac.ir
> ===========================================
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Mohnish Pandey
Y6927262,5th Year dual degree student,
Department of Chemical Engineering,
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