[Wien] Convergence tests

[Ary Ferreira]

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> 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
>>
>>
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