[Wien] [*] Re: quality FERMI surface

[Pablo de la Mora]

     You are right, I did not take into account the fact that your 
system it is body centered (I4/mmm 139), so the primitive cell is not 
'tetragonal' (F3 in xcrysden). So the k-points in each direction, that 
are not perpendicular, is about the same.

     The problem with the Fermi surfaces is that with simple symmetries 
they are OK, but with other symmetries there is a problem with XCrySDen, 
this is the case with B-tetragonal, wrinkles or undulations appear, and 
won't disappear with more k-points.
     This problem also appears with trigonal symmetry.
     If you try the P-tetragonal superconducting systems such as LaOFeAs 
or FeSe you will find very nice F.S.!

puday at iitk.ac.in escribió:
> Respected Sir,
> Thank you very much.
> Here is the full information..
> Compound - BaFe2As2
> Space Group I4/mmm
> a=b= 3.909 A
> c= 13.2122 A
> Ba= (0,0,0)
> Fe= (0.5,0,0.25)
> As= (0,0,0.3538)
>
> I tried again with lesser K points as 2000 and as usual it is making kmesh
> grid as 12x12x12.
> Could you please suggest me where is the problem and how can I solve it?
>
>
>
>    
>> In your definition you also need to give the atomic positions.
>> I feel that there is something wrong, the size of the reciprocal cell is
>> inversely proportional to the crystal cell so the k points should
>> reflect this, I tried this case (with one atom) and I got 55x55x16,
>> which is correct; 13.2122/3.909 ~ 55/16 instead of your 36x36x36
>> I don't think that you need such a large # of k-points for a fairly good
>> FS.
>>
>>      
>>> I am using WIEN2K82 with operating system Linux.The purpose of my
>>> calculation is to get quality FERMI surface.
>>> I am running the BaFe2As2.struct using this input
>>> Compound - BaFe2As2
>>> Space Group I4/mmm
>>> a=b= 3.909 A
>>> c= 13.2122 A
>>>
>>> As there is big difference in lattice constant between a and c so I am
>>> not
>>> getting a quality fermi surface for this type of structures.
>>>
>>> I am using xcrysden to get FERMI surface.I am using number of K points =
>>> 50000 as it automatically making kmesh grid as 36x36x36.
>>>
>>> So please suggest me how do I get a good quality of fermi surface for
>>> this
>>> type of structure using WIEN2K.
>>>
>>> Regards,
>>> Uday Bhanu Paramanik
>>> Research scholar
>>> c/o Dr. Zakir Hossain
>>> Dept.of Physics
>>> IIT Kanpur
>>> India.
>>> _______________________________________________
>>> Wien mailing list
>>> Wien at zeus.theochem.tuwien.ac.at
>>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>>>
>>>
>>>        
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>>      
>
> Regards,
> Uday Bhanu Paramanik
> Research scholar
> c/o Dr. Zakir Hossain
> Dept.of Physics
> IIT Kanpur
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> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>
>