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

[Cuocci Corrado]

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
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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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