[QE-users] ibrav -13

[Paolo Giannozzi]

I think that the cif file and ibrav=0 case refer to the "conventional"
cell, while the ibrav=-13 case is for the "primitive" cell. The former has
twice the number of atoms of the latter, in addition to twice the volume.
Using the information on the space group number and Wyckoff positions
contained in the cif file, you can obtain the correct (?) structure in an
easier way (see attached)

Paolo

On Sat, Sep 26, 2020 at 12:23 AM Carlo Nervi <carlo.nervi at unito.it> wrote:

>
> Dear QE developers,
> I have a problem with ibrav -13.
> The volume compute at first is too small from what it should be from a cif
> file and differs if I run with ibrav=0
>
> Attached please find the cif file, the input with ibrav=-13 and with
> ibrav=0
> With ibrav=-13 the first volume is computed as
> unit-cell volume          =    1198.4953 (a.u.)^3
>
> With ibrav=0 the first volume is computed as
> unit-cell volume          =    2396.9906 (a.u.)^3
>
> These are the step 0 of the scf calculations. The right volume seems to be
> that one with ibrav=0.
> I will appreciate any suggestions. Am I doing something wrong?
> Thank you,
> Carlo
>
> --
>
> ------------------------------------------------------------
> Prof. Carlo Nervi carlo.nervi at unito.it  Tel:+39 0116707507/8
> Fax: +39 0116707855      -      Dipartimento di Chimica, via
> P. Giuria 7, 10125 Torino, Italy.    http://lem.ch.unito.it/
>
> ICCC 2020 5-10 July 2020, Rimini, Italy: http://www.iccc2020.com
> International Conference on Coordination Chemistry (ICCC 2020)
>
>  <http://www.iccc2020.com/>
>
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users



-- 
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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20200926/a900f871/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: test_sg.in
Type: application/octet-stream
Size: 2878 bytes
Desc: not available
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20200926/a900f871/attachment.obj>