[Pw_forum] symmetry changed in vc-relaxation

[Stefano de Gironcoli]

Dear YC Cheng,
    was the symmetry recognized by the code at the beginning of the run 
and then got lost in the relaxation ... or instead the symmetry was not 
recognized and then, for numerical or physical reasons, it was not kept ?
    In the latter case it is either a numerical issue as Axel was 
suggesting or a real instability of your system toward lower symmetry.
    In the former case it may be a problem in the vc-relax part.
    please clarify the situation and provide an example if relevant.

    Stefano de Gironcoli  -  SISSA and DEMOCRITOS


程迎春 wrote:
> Dear pwscf users:
>        I performed vc-relaxation of SnO2 which has ibrav=6 
> sysmmetry(a=b!=c,cosab=cosbc=cosac=0). After the relaxation,the 
> symmtry changed(a=b!=c,cosab!=0,cosbc=cosac=0).
> Is this the code bug?
>
> -- 
> Y. C. Cheng
> Department of Phyics
> Nanjing University
> Nanjing 210093
> P. R. China
> Tel: 86-25-83592907
> Email: yccheng.nju at gmail.com <mailto:yccheng.nju at gmail.com>
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