[Wien] x symmetry problem

[Peter Blaha]

> I’m trying to run SCF cycle for a monoclinic TiO. In the data I have
> (program ICSD) for the space group is written A 1 1 2/m, #12. I saw that
> #12 in the StructGentm is B2/m. When I started xgroup I got that:
>
> sgroup found: 12 (C 2/m) [unique axis c] cell choice 2
>
> In the next step: x symmetry, I got:
> FORTRAN STOP -3 missing

Centered monoclinic cells are only partially supported by WIEN.
The monoclinic angle MUST be gamma, so you must transform your spacegroup
representation into B2/m (basically interchanging some axis and positions)
and use this representation.

Furthermore, please note that there is a yet unresolved bug for monoclinic
centered cells, which I can only summarize as: SOMETIMES the nonspherical
potential terms are wrong for this symmetry.
As SOMETIMES is not very specific, you MUST check your results using a
doubled P cell (or a triclinic P cell of same size, but no symmetry)

Regards

                                      P.Blaha
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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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