[Wien] Structure relaxation for WO3 with atomic insertion

[Laurence Marks]

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

On Sun, Jun 14, 2020, 14:26 Israel Omar Perez Lopez <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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