[QE-users] problem using vc-relax with organic crystal structure

[Claudio A. Perottoni]

Dear Corrado,

The ecutwfc in your input file seems a bit small. You may try using
https://www.materialscloud.org/work/tools/qeinputgenerator to generate an
input file for optimizing the crystal structure of your compound.
Best regards,
Claudio


On Wed, Dec 2, 2020 at 3:15 PM Cuocci Corrado <corrado.cuocci at gmail.com>
wrote:

> I have determined the crystal structure of new organic compound from
> X-ray powder diffraction data.
>
> First of all, I used quantum espresso to validate my new structure in a
> 'relax' calculation obtaining a result in a good agreement with the
> experimental structure.
>
> In a second step I tried to perform a 'vc-relax' but in this case the
> result seems chemically unreasonable: I observed a large variation of
> the cell parameters, final density too high for this type of compound,
> short intermolecular distances.
> Input and output files can be downloaded from:
> https://cloud.ba.cnr.it/index.php/s/5RmA7MqA9gJeRdx/download
> https://cloud.ba.cnr.it/index.php/s/qmnAwM5JeqDnHdG/download
>
> My experience in the use of the program is limited and I suspect I have
> made some mistakes.
> Do you have any suggestions to improve the calculation?
>
> Thanks a lot.
> Corrado
> --
> ============================================
> Cuocci Corrado
> Istituto di Cristallografia - CNR
> Via G. Amendola,122/o
> 70126 Bari (Italy)
> tel: +390805929161
> fax:+390805929170
> corrado.cuocci at ic.cnr.it
> ============================================
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>


-- 

*Claudio A. Perottoni*

Universidade de Caxias do Sul
95070-560 Caxias do Sul - RS - Brazil
http://www.researcherid.com/rid/B-8409-2008
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