[Wien] Structure relaxation for WO3 with atomic insertion

[Israel Omar Perez Lopez]

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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