[QE-users] not orthogonal operation in dos.x run only

[Paolo Giannozzi]

Obscure symmetry problems almost invariably come from the usage of "free"
Bravais lattice (ibrav=0) and almost-symmetric-but-not-enough lattice
vectors, or by almost-symmetric-but-not-enough atomic positions

Paolo

On Sat, Oct 3, 2020 at 6:36 PM Lucas Dória <lucasdoriacarvalho at hotmail.com>
wrote:

> Dear all,
>
> I ran into this problem while doing a dos.x calculation (nscf and scf
> calculations finished succesfully):
>
> *'from checkallsym : error # 2*
> *not orthogonal operation'*
>
> The structure is a WS2 bilayer. (WS2 is a layered material, we optimized
> bulk structure and then added vaccum in z-direction to get bilayer
> structure.)
>
> When i looked up for possible reasons and solutions, I found this problem
> only occuring in vc-relax calculations. Our group did in fact optimized the
> hexagonal structure, but vc-relax calculations finished succesfully.
>
> I add that we already studied electronic properties of another very
> similar hexagonal structure, of the same point group, namely MoS2, and we
> didn't get symmetry issues. (using v5.4 at the time)
>
> So, I don't know why this problem of 'not orthogonal operation' is
> happening to WS2, and just in dos.x calculation, if it's a crash due to
> symmetry breaking. We think that the only major differences between WS2 and
> MoS2 are that W is heavier than Mo, and the PP used. But we are using an
> optimized ecutwfc.
>
> Thanks in advance. QE-version used: 6.5.
>
> Lucas.
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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