As was mentioned before:
For cubic, all your atoms are on high symmetry positions with (by
symmetry) fixed positions. (It is like a NaCl structure). The code tells
you: Forces are not present and there is nothing to optimize.
So all you can do with this symmetry is a volume optimization, or you
displace the atoms a bit from these high symetry positions, to allow for
lower symmetry which gives forces and positions which can be optimized.
What I would do:
Cubic:
init -b -numk 100 -rkmax 6
x optimize
edit optimize.job and increase convergence to -ec 0.00001
./optimize.job
eplot -a default
Evenutally you have to repeat x optimize in case that the minimum was
not in the selected range.
This gives you a first estimate of the volume. The calculations are not
well converged (k-mesh, RMT, rkmax), but it should suffice to give an
estimate where approximately the minimum is. For the structure closest
to the minimum run
x nn and check the "Bond valence sum (BVS). These numbers should be
close to chemical intuition (Li +1, O 2-,..)
Other symmetries:
init -b -numk 100 -rkmax 6
x optimize and always do a VOLUME optimization first, option1)
edit optimize.job and activate optimization of internal positions
SIMULTANEOSLY for each volume: Change the run_lapw line and add
-min -fc 1 (this is listed after the comment symbol (#) anyway.
If you want, you can then do a c/a optimization for the best volume.
Check all BVS for the relaxed structures.
Once you have a crude minimum for all 3 structures, start over with the
minimum structures and
choose ONE (consistent) set of RMTs for all structures
initialize with "better parameters" (k-mesh, RKmax)
Do again x optimize (including -min for the non-cubic structures)
and compare these minimum with the previous (crude) solution (it should
change only little) and compare the energies of the structures.
PS: If during the first optimization a nn-overlap, no reasonable step
error occurs, use reduce_rmt to reduce the RMTs and continue.
Am 14.06.2020 um 23:53 schrieb Israel Omar Perez Lopez:
I just want to study the effect of Li insertion in the optical
properties of WO3. But first I have to obtain the atomic positions and
lattice parameters after Li insertion in those three structures.
So, in particular, I would like to know the steps I have to follow to
obtain this information. Do I have to do force minimization and volume
optimization, simultaneously? Or should I do minimization first and then
volume optmization after? or viceversa? And how do I do this?
I would appreciate any information on how to proceed.
Best Regards
Dr. Israel Pérez
Institute of Engineering and Technology
Department of Physics and Mathematics,
Universidad Autónoma de Ciudad Juárez
Av. del Charro 450 Nte., Col. Partido Romero,
Ciudad Juárez, Juarez Chihuahua. Mexico C. P. 32310
Tel: +52 (656) 688 4887
National Council of Science and Technology
Insurgentes Sur No. 1582,
Col. Crédito Constructor, C.P. 03940
Del. Benito Juárez, México D. F.
------------------------------------------------------------------------
*From:* Wien <[email protected]> on behalf of
Laurence Marks <[email protected]>
*Sent:* Sunday, June 14, 2020 3:35 PM
*To:* A Mailing list for WIEN2k users <[email protected]>
*Subject:* Re: [Wien] Structure relaxation for WO3 with atomic insertion
To repeat, in cubic all your atoms are at high symmetry sites so
internal relaxation is not possible. User error, the program is telling
you. Please think it through.
N.B., to compare at the end you will need to convert everything to the
smallest RMTs.
_____
Professor Laurence Marks
"Research is to see what everybody else has seen, and to think what
nobody else has thought", Albert Szent-Gyorgi
www.numis.northwestern.edu <http://www.numis.northwestern.edu>
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Inst.Materials Chemistry
TU Vienna
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