[Wien] Large oscillations in total energy

[Pavel Ondračka]

Dear Wien2k mailing list,

I'm seeing some strange energy oscillations in one calculation near the
end when everything seems almost converged.

:ENERGY convergence:  0 0.0001 .0039009700000000
:ENERGY convergence:  0 0.0001 .0168906450000000
:ENERGY convergence:  0 0.0001 .0096598000000000
:ENERGY convergence:  0 0.0001 .0162053350000000
:ENERGY convergence:  0 0.0001 .0089683200000000
:ENERGY convergence:  0 0.0001 55.6398533450000000
:ENERGY convergence:  0 0.0001 27.8210445050000000
:ENERGY convergence:  0 0.0001 27.8235252600000000

the charge is converged already:

:CHARGE convergence:  1 0.001 -.000920
:CHARGE convergence:  1 0.001 -.000977
:CHARGE convergence:  1 0.001 -.000933
:CHARGE convergence:  1 0.001 -.000972
:CHARGE convergence:  1 0.001 -.000984
:CHARGE convergence:  1 0.001 -.000988
:CHARGE convergence:  1 0.001 -.000997
:CHARGE convergence:  1 0.001 -.000998

This is quite large calculation of TiSiO amorphous-like cell (96 atoms,
 struct file attached, compressed in order to pass the moderation
queue). The numerical parameters are quite standard,
2x2x2 shifted k-grid (can also reproduce this with 3x3x3), Rkmax 7.5,
PBE, rest of stuff at default. I have done a lot of calculation with
similar cells and such parameters without any problems (albeit mostly
some time ago with older Wien2k versions)...

I'm trying to calculate the binding energy of the O 1s for the first
oxygen using the Slaters transition state approach. Surprisingly when I
use almost touching spheres it converges (O:1.48, Ti: 1.72, Si:1.48),
however when I reduce them by 3% (as in the attached struct file) this
problems surfaces. However I need this reduced spheres for comparison
with another calculation. BTW the spheres around 1.5 for oxygen
should be reasonable anyway?

No errors or warnings anywhere, except for the expected 
WARN  :        CHARGED CELL with  -0.500

This is with Wien2k 17.1, compiled with MKL 2017.0.098 and ifort.

Any ideas what might be causing this problem?
Best regards
Pavel
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