[Wien] P21/c (n°14) space group

[cbridges at liverpool.ac.uk]

Dear all,
I would like to take this opportunity to inquire again for clarification about
the "Symmetry does not work for monoclinic lattice" FAQ on the Wien2K web page.
Can someone please suggest a good value of the monoclinic angle to use? 90.1 or
90.01 deg, for example?

Regards,
Craig



Quoting Peter Blaha <pblaha at zeus.theochem.tuwien.ac.at>:

> > I think there is a problem in the way equivalent (4e) positions are built
> > for P21/c space group. To show that I put the struct file generated
> > recently which is not correct and one built with an older version which is
> ok.
> !!!!!!!!!!!!ATTENTION!!!! this BUG could easily affect
> you!!!!!!!!!!!!!!!!!!!!
> 
> Thank you very much for this report.
> Yes, I can verify the problem. It is due to a modification I made some weeks
> ago. The "old" version forced you to input an angle ne. 90 degree for a
> monoclinic spacegroup. Since in principle it should be allowed to use
> a monoclinic spacegroup, but put (just by chance) all angles to 90, I wanted
> to remove this restriction. While I could remove it, this program does not
> work correctly anymore. I'll change it back.
> 
> PLEASE note: Low symmetry spacegroups might have wrong positions when
> generated with "spacegroup"-version LATER than 6.Nov.2003  !!!!!!!!!!!
> 
> The "old" (correct) version will be on the web soon.
> 
>                                       P.Blaha
> --------------------------------------------------------------------------
> 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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