[Wannier] Dissimilar results in band structures for a system obtained from Wannier90

Wed Jun 10 12:29:38 CEST 2015

Dear Prof. Marzari

As you suggested I checked input files and they were exactly identical. but
the difference in result remains.
I tried to make a change in calculations so I increased number of kpoints
in non scf and wannier calculations from
a mesh of 12*12*1 to 16*16*1. The result was an improvement in band
structure. you can find the plot attached. But
there are still some inadequacies to the pw band in the region gamma to X.
Again I increased the grid to a 24*24*1 mesh which encountered this error:

Unable to satisfy B1 with any of the first  12 shells
 Your cell might be very long, or you may have an irregular MP grid
 Try increasing the parameter search_shells in the win file (default=12)

Setting the parameter search_shells = 60 solved the problem but now
inadequacies are in the region S to Y (the plot is attached).
I don't know if there is any parameter that I could change to solve this
problem. Please give me any probable hint.
Thanks,

On Wed, Jun 10, 2015 at 2:53 PM, Seyed Mojtaba Rezaei Sani <
s.m.rezaeisani at gmail.com> wrote:

> Dear Prof. Marzari
>
> As you suggested I checked input files and they were exactly identical.
> but the difference in result remains.
> I tried to make a change in calculations so I increased number of kpoints
> in non scf and wannier calculations from
> a mesh of 12*12*1 to 16*16*1. The result was an improvement in band
> structure. you can find the plot attached. But
> there are still some inadequacies to the pw band in the region gamma to X.
> Again I increased the grid to a 24*24*1 mesh which encountered this error:
>
> Unable to satisfy B1 with any of the first  12 shells
>  Your cell might be very long, or you may have an irregular MP grid
>  Try increasing the parameter search_shells in the win file (default=12)
>
> Setting the parameter search_shells = 60 solved the problem but now
> inadequacies are in the region S to Y (the plot is attached).
> I don't know if there is any parameter that I could change to solve this
> problem. Please give me any probable hint.
> Thanks,
>
> On Thu, May 28, 2015 at 12:39 PM, Nicola Marzari <nicola.marzari at epfl.ch>
> wrote:
>
>>
>>
>> Well, the obvious thing to do is making sure your
>> inputs are exactly identical, you re-run the calculations
>> to make sure the error shows up again, and then you start
>> doing a diff in the output files of quantum-espresso, and
>> see where there is a difference.
>>
>>                                 nicola
>>
>>
>>
>>
>> On 28/05/2015 09:07, Seyed Mojtaba Rezaei Sani wrote:
>>
>>> Dear Wannier90 users,
>>>
>>> I am trying to calculate wannier functions for phosphorene using
>>> wannier90. first I tried to plot band structure using both
>>> quantum-espresso and wannier90. Results were in good agreement. Now I
>>> have upgraded espresso to 5.1.2 version but with the same inputs the
>>> obtained results are not similar.
>>> All files are attached and here in .win input:
>>>
>>> num_bands        = 10
>>> num_wann         = 10
>>> num_iter         = 500
>>>
>>> Begin Unit_Cell_Cart
>>> Bohr
>>>      6.282237122     0.000000000     0.0000000000
>>>      0.000000000     8.651074073     0.0000000000
>>>      0.000000000     0.000000000     26.456165734
>>> End Unit_Cell_Cart
>>>
>>> Begin Atoms_Frac
>>> P1        0.010000000   0.086656382   0.152592466
>>> P1        0.010000000   0.913343530   0.001000000
>>> P2        0.510000000   0.413343618   0.152592466
>>> P2        0.510000000   0.586656470   0.001000000
>>> End Atoms_Frac
>>>
>>> Begin Projections
>>> P1:sp3
>>> P2:py
>>> End Projections
>>>
>>> bands_plot = true
>>>
>>> begin kpoint_path
>>> G 0.0000 0.0000 0.0000 X 0.5000 0.0000 0.0000
>>> x 0.5000 0.0000 0.0000 S 0.5000 0.5000 0.0000
>>> S 0.5000 0.5000 0.0000 Y 0.0000 0.5000 0.0000
>>> Y 0.0000 0.5000 0.0000 G 0.0000 0.0000 0.0000
>>> end kpoint_path
>>>
>>> mp_grid = 12 12 1
>>>
>>> begin kpoints
>>>    0.00000000  0.00000000  0.00000000
>>>   .
>>>   .
>>>   .
>>>    0.91666667  0.91666667  0.00000000
>>> End Kpoints
>>>
>>> I would greatly appreciate it if you kindly give me some hints.
>>>
>>> Best regards,
>>>
>>> --
>>> Seyed Mojtaba Rezaei Sani
>>>
>>> Institute for Research in Fundamental Sciences (IPM)
>>> School of Nano-Science
>>> Shahid Farbin Alley
>>> Shahid Lavasani st
>>> P.O. Box 19395-5531
>>> Tehran, Iran
>>> Tel: +98 21 2310  (3069)
>>>
>>>
>>> _______________________________________________
>>> Wannier mailing list
>>> Wannier at quantum-espresso.org
>>> http://mailman.qe-forge.org/cgi-bin/mailman/listinfo/wannier
>>>
>>>
>> --
>>
>> ----------------------------------------------------------------------
>> Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
>> Director, National Centre for Competence in Research NCCR MARVEL, EPFL
>>
>
>
>
> --
> Seyed Mojtaba Rezaei Sani
>
> Institute for Research in Fundamental Sciences (IPM)
> School of Nano-Science
> Shahid Farbin Alley
> Shahid Lavasani st
> P.O. Box 19395-5531
> Tehran, Iran
> Tel: +98 21 2310  (3069)
>

-- 
Seyed Mojtaba Rezaei Sani

Institute for Research in Fundamental Sciences (IPM)
School of Nano-Science
Shahid Farbin Alley
Shahid Lavasani st
P.O. Box 19395-5531
Tehran, Iran
Tel: +98 21 2310  (3069)
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