[Wien] Convergence tests

[Peter Blaha]

Without details we cannot make any statement.

Only:
i) SMALL changes are possible due to different WIEN2k versions or some 
parameters not mentioned in the paper.
ii) If there is "real" disagreement, either the authors of the paper or 
you have made an error.
iii) Quoting: "the asymmetry parameters differ by 0.05321 and 0.11776"
means that you did not check/understand your convergence properly. It is 
MEANINGLESS to quote eta with more than 2 digits (0.05 is fine, but 
0.05321 is nonsense).
iv) After "relaxation" of a structure, the forces must be small. If not, 
something went wrong or you made a mistake.

On 04/05/2015 11:07 PM, Ary Ferreira wrote:
> Hi,
>
> The experimental values for the quadrupolar frequencies and the
> asymmetry parameter could be obtained with high accuracy for the
> material under study. The point is that in this work, these properties
> are being reported for the experimental structure and also for the
> equilibrium structure with forces smaller than 0.1 mRy. Actually the
> quadrupolar frequencies at experimental positions are in a very good
> agreement with their WIEN2k results, but the asymmetry parameters differ
> by 0.05321 and 0.11776, for the same structure. And more, when I try to
> reproduce the results at the supposed relaxed structure, both properties
> are quite different, the quadrupolar frequencies differ by more than 20
> kHz. Additionally, with the relaxed structure, the forces in my case.scf
> are higher than 40 mRy after converge everything. Since I'm using the
> same structures, I was expecting to have the "same" numbers.
>
> Thank you very much for your attention,
>
> Ary Ferreira
>
>
>
> On Sun, Apr 5, 2015 at 10:36 PM, <tran at theochem.tuwien.ac.at
> <mailto:tran at theochem.tuwien.ac.at>> wrote:
>
>     Hi,
>
>     What do you mean by "exactly"? What are the differences between the
>     published results and yours?
>
>     F. Tran
>
>
>     On Sun, 5 Apr 2015, Ary Ferreira wrote:
>
>         Please,
>
>         I'm trying to reproduce a result obtained with WIEN2k from a
>         publication. I'm using the same structure, which is a monoclinic
>         cell with the C2/c space group. So, I used the program
>         SETSTRU to transform it from the space group C12/c1 to B112/b.
>         Regarding the WIEN2k calculation, the authors reported the MT
>         radii, the product of the minimal MT radius and the cut-off
>         for the PW basis set Kmax (RmtxKmax), the maximal value of l in
>         the expansion of the PW in spherical harmonics (lmax), the
>         highest l in the expansion of the potential in lattice harmonics
>         (lpot), and the k-points sampling.
>
>         I tested the following parameters (in the order listed below)
>         for the convergence of the total energy, the main component of
>         the electric field gradient tensor, and its asymmetry
>         parameter.
>
>         - the k-points sampling using "x kgen" and selecting different
>         number of k-points;
>         - the value of RmtxKmax from 6.0 to 9.0 in steps of 0.5;
>         - the cutoff for the potential (and charge density) Gmax from 12
>         to 20 in steps of 2;
>         - lmax = 12, 13, and 14;
>         - lpot = 4, 5, and 6;
>
>         Additionally, I also tried to reduce the MT radii by 0.05% and
>         0.1%, and tested again the RmtxKmax. However, I'm not being able
>         to reproduce "exactly" the reported theoretical results. I
>         just want to know what else can be done to improve the obtained
>         observables. If there is some document I have missed, please I'm
>         sorry.
>
>         Thank you very much!
>
>         Ary Ferreira
>
>         --
>         http://lattes.cnpq.br/__8221674673413336
>         <http://lattes.cnpq.br/8221674673413336>
>
>
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-- 

                                       P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
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