unwrapped ions during CELL_OPT

[Pierre-André Cazade]

Dear CP2K users,

I am running a CELL_OPT on a 280 atoms unit cell. It was poorly resolved experimentally, yet I am surprised that some atoms wander out of the unit cell and are not wrapped back in. It is quite unexpected. According to the following topic: https://groups.google.com/forum/#!topic/cp2k/rqOO2W04OPc , CP2K does not wrap atoms, at least in MD mode. This is very strange. Is it intentional? Is it a bug? And does it affect in any kind of way calculations?

I am bothered by the optimized structure which shows a considerable increase of the "a" parameter. Again, I compared with VASP and the final structure with the latter is much more reasonable. I do not expect identical optimized structure but they should not drift so much away from each other. Could this lack of wrapping explain the divergence or it comes from inadequate SCF parameters?

I attached the input file and the final restart file.

Regards,

Pierre

[Pierre Cazade]

Hi,

Thank you for your suggestion. I will try to run again the cell_opt as you suggest. The question remains, why VASP leads to a different structure, expended yes but not to that extend. Both a and c reach about 9.2 and b reaches 43.

Regards,
Pierre

On 25/10/2019 15:44, Travis wrote:

Hi,

Your input structure is very compressed. It should expand and your final structure looks much more reasonable. The amount it is expanding by, I would actually suggest redoing the CELL_OPT from the final structure as your effective cutoff decreases when the cell volume increases. Coordinates are unwrapped intentionally in all calculations. You can impose PBC to wrap the coordinates using an external program. I recommend Atomic Simulation Environment,

Grab last image from foo-pos-1.xyz:

https://github.com/pollardtp/asepylot/blob/master/general/pos2xyz.py

Add cell parameters from command line args:

https://github.com/pollardtp/asepylot/blob/master/general/xyz2vasp.py

Generated structure is in POSCAR format, viewable with VESTA. Adapt to your suiting.

Delete this bit, it's specific to my setup.

from require import check_ase
check_ase()

-T

--
You received this message because you are subscribed to the Google Groups "cp2k" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cp2k+uns...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/325eba17-1ca3-4a42-bb09-9da313b118bb%40googlegroups.com.

-- 
Dr Pierre Cazade, PhD
AD3-023, Bernal Institute,
University of Limerick,
Plassey Park Road,
Castletroy, co. Limerick,
Ireland

[Yingchun Zhang]

what do you mean with " MULTIPLICITY  0" in your input file, it's 2s+1

[Patrick Gono]

Dear Yingchun,

The default MULTIPLICITY value of 0 evaluates to 1 in the case of an even number of electrons (singlet) and to 2 in the case of an odd number of electrons (doublet).

Yours sincerely,

Patrick Gono

On Tue, Nov 5, 2019 at 3:43 PM Yingchun Zhang <zhangyin...@126.com> wrote:

what do you mean with " MULTIPLICITY  0" in your input file, it's 2s+1

--

You received this message because you are subscribed to the Google Groups "cp2k" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cp2k+uns...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/d7f11e20-a5d6-45eb-b79d-2e2abbcfb972%40googlegroups.com.