[Wien] SCF convergence

[Laurence Marks]

It is unlikely that anyone will be able to help without the
case.struct file (as a minimum). I suspect that you have something
wrong with the structure, for instance inappropriate symmetry,
distances, or similar. As a basic point, it is best to use the
defaults unless you have a good reason (one is the # k-points with
larger cells), so GMAX 20 & RKMAX 9.0 are probably not appropriate as
well as Emax 5 as you do not have -so.

A simple thing to do is "x patchsymm" and see what that tells you, it
picks up many errors.

Also, you a viewer to look at your structure to see if it is sensible.

Switching from MSR1 to PRATT won't help, and will almost certainly
make things worse.


On Wed, Sep 25, 2013 at 9:22 AM, Luis Ogando <lcodacal at gmail.com> wrote:
> Dear Wien2k community,
>
>    We are trying do calculate the influence of zinc blend (ZB) stacking
> faults on InP (sp semiconductor) wurtzite (WZ) systems using Wien2k 13. Our
> first goal is to calculate the band gap change along the c-axis
> (perpendicular to the interface between the two phases), similar to what was
> done in J. Appl. Phys. 114, 033709 (2013) for two semi-infinite structures.
>    In our case, we use a supercell with three ZB cells along (111)
> (hexagonal form) matched along "c" to a large sequence of WZ cells to
> guarantee a minimum reproduction of a ZB environment in the stacking fault
> region.
>    We have done calculations for a system with 10 WZ cells, but the gap did
> not change along the structure and we are now trying 15 WZ cells and the 3
> ZB ones (78 atoms in total) to isolate neighbour stacking faults.
>    As the gap is our main property, we are using the mBJ potential, but we
> are facing convergence problems at the first (PBE) SCF calculation.
>    We would be glad if someone could give us any hint about how to improve
> the PBE scf convergence.
>    Here we give some relevant parameters of our calculation (please, do not
> hesitate in asking others):
>
> *Species: "In" and "P"
> *Number of atoms: 78
> *RMT: 2.50 (In) and 2.10 (P)  (NN-DIST= 4.84768)
> *RKmax: 9
> *Emax: 5 (spin-orbit effects)
> *XC: 13 (PBE)
> *core-valence separation energy: -6.0
> *GMAX: 20
> *Inequivalent Kpoints: 12 increased to 24 after some iterations
> *Mixing schema: MSR1 changed to PRATT with 0.15 mixing factor after some
> iterations
> *Calculation options: run_lapw -p -NI -ec 0.0001 -cc 0.0001 -i 150 -it
> ** We also attached the energy (Energy.dat) and charge (Charge.dat)
> convergence evolution.
>
>
>    Many thanks in advance.
>    All the best,
>                     Luis



-- 
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu 1-847-491-3996
"Research is to see what everybody else has seen, and to think what
nobody else has thought"
Albert Szent-Gyorgi