Dear Cyrille,
from the input description:
'xy' : only v1_x and v2_y are moved
'2Dxy' : only x and y components are allowed to change
Thus, even in the case of cell_dofree='xy' I think the cell will change.
Anyway, the deviation from 120 DEG is quite small (119.43 DEG if I'm not
wrong) - I don't know if this could be do to numerical issues. Maybe try
starting a new relaxation with a hexagonal cell but smaller in-plane
lattice vector of ~99.1%
Cheerio
Thomas
On 07/25/17 09:08, BARRETEAU Cyrille wrote:
Dear QE community
I have a question related to vc-relax and the option cell_dofree.
I want to relax a 2D metal-organic framework (MOF) with hexagonal
lattice (ibrav=4)
Could you please explain what is the difference between cell-dofree=xy
and cell_dofree=2Dxy?
I have noticed that when using cell_dofree=2Dxy the final
CELL_PARAMETER is no longer perfectly hexagonal (see below). Should I
use cell_dofree=xy instead and why?
final:
CELL_PARAMETERS (alat= 25.44640422)
0.990921488 -0.000187347 0.000000000
-0.495622997 0.858299558 0.000000000
0.000000000 0.000000000 0.742630080
Thanks in advance
Cyrille
========================
*Cyrille Barreteau*
CEA Saclay, IRAMIS, SPECBat. 771
91191 Gif sur Yvette Cedex, FRANCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+33 1 69 08 38 56 /+33 6 47 53 66 52 (mobile)
email: [email protected]
Web: http://iramis.cea.fr/Pisp/cyrille.barreteau/
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Dr. rer. nat. Thomas Brumme
Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry
Leipzig University
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