[Thermo_pw-forum] Point group orientation incorrect

[Andrea Dal Corso]

There are missing symmetries in your geometry and the
symmetry is not compatible with the hexagonal lattice.
I would try to understand why. Please see the pw.x user's guide.

Andrea

Quoting Elio Physics <Elio-Physics at live.com>:

> Dear all,
>
> I am trying to perform elastic constant calculations on a  
> hexagonal/trigonal system using thermo_pw. The code stops and  
> complains:
>
> C_s (m) is incompatible with the one face centered orthorhombic (C)  
> Bravais lattice
>      It is compatible with the
>      monoclinic (c unique) Bravais lattice; ibrav=   12
>      base centered monoclinic (c unique) Bravais lattice; ibrav=   13
>      monoclinic (b unique) Bravais lattice; ibrav=  -12
>      base centered monoclinic (b unique) Bravais lattice; ibrav=  -13
>
> I tried to define the lattice as ibrav=12 and tried outsmarting the  
> code by giving the parameters of a trigonal structure that is  
> celldm(1)=..., celldm(2)=1, celldm(3)=6.3 and celldm(4)= -0.5
>
> However the code stopped again with th error:
>
>  Error in routine find_space_group (1):
>      point group orientation incorrect
>
> I am not really sure what to do. What could the source of this error be?
> Is it possible to tell the code to take the system as it is defined  
> in the inout file , that is ibrav=4?
>
> Any help would be appreciated.
>
> Elie
> Federal University of Rondonia
> Brazil