[Wien] Structure relaxation for WO3 with atomic insertion

Sun Jun 14 23:23:28 CEST 2020

Dear Prof. Marks

Thanks for your reply. My intention is to find out the optimized positions and lattice parameters after Li insertion in those three structures. As I understand, to obtain this I have to do both force minimization and volume optimization, simultaneously, am I right? Or should I do minimization first and then volume optmization after? or viceversa? I would like to know the steps I have to follow to obtained this information.

I have already checked the mailinglist, the UG, the internet, and the old notes you mention. I am trying to work systematically, my email is after trying in many ways. I have worked minimization alone (both PORT and MSR1a) and it converges for hexagonal and monoclinic but not for cubic due to the error I mentioned. Optimization alone applied for monoclinic and hexagonal does not reach a minimum with Li insertion.

I will try to answer your points.

1) in your cubic case all internal parameters are fixed by symmetry, hence you cannot optimize them.

I already carried out optimization alone and a minimum is reached without Li and with Li. The problem is when I run force minimization to find the atomic positions, this error show up: Force-convergence not possible. Forces not present

2) What version are you using? Nowadays MSR1a has mainly replace min (PORT).

I'm using Wien2k 19.1. So again, my question is if I run minimization first and then volume optimization. I have run both PORT and MSR1 alone and force convergence is achieved. But should I used these new positions to find the lattice parameters?

3) Did you check (look) at all the structures first, and the BVS? You may save yourself a lot of time and avoid simple errors.

Yes, I have checked the structure files.

4) To make comparisons, you will need to use identical parameters (RMT etc).

The spacing available for Li insertion for cubic, hexagonal and monoclinic is not the same. If I used the same RMT in all three cases, during optimization an error related to sphere overlapping shows up as the lattice parameters change for each structure (say 8%, 4%, 0%, -4% and -8%).

I suggest that you do the simple cubic case first and optimize the volume.
I have already done volume optimization for cubic. For both cases (Li and no Li) a minimum was reached. Here no problem, but what about atomic positions when Li is inserted? I got the error:
Force-convergence not possible. Forces not present

Please advice the right procedure to get lattice parameters and atomic positions.

Regards

Dr. Israel P?rez

Institute of Engineering and Technology
Department of Physics and Mathematics,
Universidad Aut?noma de Ciudad Ju?rez
Av. del Charro 450 Nte., Col. Partido Romero,
Ciudad Ju?rez, Juarez Chihuahua. Mexico C. P. 32310
Tel: +52 (656) 688 4887

National Council of Science and Technology
Insurgentes Sur No. 1582,
Col. Cr?dito Constructor,  C.P. 03940
Del. Benito Ju?rez, M?xico D. F.
________________________________
From: Wien <wien-bounces at zeus.theochem.tuwien.ac.at> on behalf of Laurence Marks <laurence.marks at gmail.com>
Sent: Sunday, June 14, 2020 1:52 PM
To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
Subject: Re: [Wien] Structure relaxation for WO3 with atomic insertion

Many things:
1) in your cubic case all internal parameters are fixed by symmetry, hence you cannot optimize them.
2) What version are you using? Nowadays MSR1a has mainly replace min (PORT).
3) Did you check (look) at all the structures first, and the BVS? You may save yourself a lot of time and avoid simple errors.
4) To make comparisons, you will need to use identical parameters (RMT etc).

I suggest that you do the simple cubic case first and optimize the volume. Check it is sane with reasonable BVS etc. This will give you a good idea what RMTs to use for the other cases (you may need to iterate). Work it through, being systematic and understanding each step (not just read very old notes).

_____
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>

On Sun, Jun 14, 2020, 14:26 Israel Omar Perez Lopez <israel.perez at uacj.mx<mailto:israel.perez at uacj.mx>> wrote:

Dear Wien2k experts

I am trying to do structure relaxation for WO3 with Li+ insertion for three different phases: cubic [SG Pm-3m (221)], hexagonal [SG P6/mmm (191)] and monoclinic [SG=P21/n (14)] (no supercell in all cases).

For monoclinic I am working with

a=13.8066, b=14.2485 and c=14.5357, alpha=90, beta=90.881, gamma=90; with O1 x=0.284, y=0.2605, z=0.2848; O2 x=0.2827, y=0.0383, z=0.0046; O3 x=0.0025, y=0.035, z=0.2106; O4 x=0.2099, y=0.2568, z=0.7318; W1 x=0.2538, y=0.0353, z=0.7807; W2 x=0.2465, y=0.0269, z=0.2859; O5 x=0.2856, y=0.4840, z=0.9944; O6 x=0.9974, y=0.4636, z=0.2161; Li

x=y=z=0.5. With RMT for O=1.50, W=1.70 and Li=1.35.

For the initialization I used default parameters except RKmax=6 and a k-mesh of 4X4X4 (all atoms were set to nonmagnetic).

To do relaxation I ran optimize with option 7 .This asks for the number of structures which I set to 15 and 3% of difference for each structure. Then I set the otimize.job script to

min -I -j "run_lapw -I -ec 0.001 -cc 0.001 -fc 5.0 -i 40 -p"

as suggested by L. D. Marks in the optimization notes. The program stopped due to an error related to sphere overlapping between O and W. I guess this problem is related to a big percentage (3%) so I started over, also set 15 structures but 1% of difference with

min -I -j "run_lapw -I -ec 0.001 -cc 0.001 -fc 2.0 -i 40 -p"

This time the following errors showed up after a day of doing calculations:

Cholesky INFO = 4263

'SECLR4' - POTRF (Scalapack/LAPACK) failed.

And an error in mini.error

STOP in MINI, FORCES small

I don't know if the first error caused the second one or viceversa. What I am doing wrong?

For the hexagonal case I am using this:

a=b=13.7912 Bohr, c=7.3680 Bohr, alpha=beta=90, gamma=120, and positions W, x=0.5, y=z=0, O1 x=z=0.5 y=0 and O2 x=0.212, y=0.424 and z=0 with RMT values of W=1.7, O=1.5 and Li=1.35. Default initial parameters with a k-mesh 4X4X8.

To do relaxation I ran optimize with option 2 (for C/A ratio) and set the percentages to (15,7,0,-7,-15)% (before I also tried 12, 6, 0, -6, -12 no minimium either, linear distribution), then I set the script  optimize.job to

min -I -j "run_lapw -I -ec 0.001 -cc 0.001 -fc 5.0 -i 40 -p"

The forces converged but no minimum point was observed in energy vs volume, the point distribution was not parabolic although the fitting was a parabola. Am I doing something wrong?

For the cubic case I am using a=7.056237 Bohr, W  x=x=z=0 and O x=0.5, 0, 0. RMT for W=1.83 and O=1.57. Li is inserted at Li x=y=z=0.5  with  RMTLi=1.5. Initialization is with default parameters except  a k-mesh 4X4X8. Then I run an scf cycle with fc=1.0 but the program immediately stops showing up an error reading this:

 LAPW0 END

Force-convergence not possible. Forces not present.
grep: lapw2*.error: No such file or directory

The same happens if I try to run minimization with either mode.

Could you please advice what is the right way to proceed for structure relaxation in these three cases? I would appreciate it.

Best regards

Israel

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