[QE-users] Fixing atomic positions while vc-relax with cell_dofree

[Antoine Jay]

Dear users,
Is there any way to fix atomic positions while relaxing the unit-cell with cell_dofree?
I tried cell_dofree='z'
with
ATOMIC_POSITIONS (angstrom)
Atome1  X Y Z          [some unfixed positions]  
Atome2  X Y Z 0 0 0 [some fixed positions]


But the fixed atomic positions still move along 'z' even when their forces are multiplied by 0.
The code goes from angstrom to crystal coordinates:
the atomic positions are preserved in crystal coordinates but not in angstrom coordinates!
... meaning that the inter-atomic distance is not preserved.

Regards,

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Antoine Jay                                       LAAS-CNRS
ajay at laas.fr                       7, Avenue du Colonel Roche                         
(+33)5 61 33 79 56        BP 54200, 31031 Toulouse cedex 4         
Equipe M^3               Modélisation Multi-niveaux des Matériaux  
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