[Wien] Symmetry pts in Brillouin zone

[J. K. Balamurugan]

Dear Peter sir,

Thanks for your inputs.

I have made basic DOS & band structure calculations for at least 10
different compounds of different structure. I have been using the "Create
case.klist_band" button whenever XCrysDen does not work.

I also noticed that there are  bcc, fcc, hcp, simple_cubic and from xcrysden
pulldown options, but I never chose anything from them but simply click on
the "Create case.klist_band" and proceeded the calculations. I have done the
same way for simple cubic, bcc, fcc, tetragonal, orthorhombic, monoclinic
crsystals and repeated the calculations for many of them.

My doubt now is that whether it is OK if I click on the "Create
case.klist_band" button and proceed the calculations for whatever be the
symmetry of the crystal and Wien2k will take care of the right high symmetry
points in IBZ with a suitable sequences?

*Please read the below if you need more inputs regarding my calculations and
results related to this problem:*

I found that though I do not select any template specific to the crystal
system/structure of the compound I work with, the band structure comes out
with different symmetry points (symbols) for differenct crystal structure
and they are reproduced if the calculations are made for the same crysstal
structure (of the same compound.)

For example: I made a calculation for CuFeS2 chalcopyrite (tetragonal I-42d)
structure. I made three different calculations each one with the assumption
that the compund is (i) non-magnetic/paramagnetic, (ii) ferromagnetic with
Fe moments up, and (iii) antiferromagnetic with 50% Fe moments up and
50% down. In the case (i) and (ii) the band structure plot came with the
symmetry points Gamma, Delta, H, N, Sigma, Gamma, Lamda and P. This is the
same sequence which is coming for any compound with same tetragonal I-42d
sturture; I have done such calculations for another 2 more compounds. In
case (iii) in order to implement the antiferromagnetism I represented the
crystal data using P1 space group since in I-42d Fe has only one set of
fractional coordinates. This changed the shape and symmetry of the BZ which
I was able to view in XCrysDen while beginning my calculations.
Unfortunately, XCrysDen did not run while I calculate the band structure. So
I used the  "Create case.klist_band" button without selecting any template.
I got the band structure with the high symmetry points R, Lamda, Gamma,
Delta, X, Z, M, Sigma, Gamma. (This points with same sequence came in the
band structure of another compound of the type of formula A2BCD4
which actually has monoclinic structure - Pn space group.) Therefore, I
concluded that Wien2k takes care of a set of high symmetry k-points (though
it may be having a random path) in a sequence which is specific to the
symmetry of the crystal system/lattice that is uesed in the calculations.

Thanks for the kind help.


On Thu, Sep 15, 2011 at 3:08 AM, Peter Blaha
<pblaha at theochem.tuwien.ac.atp>wrote:

> Just a short reminder:
> Have you noticed the filed left to "Create case.klist_band" Button ???
>
> Wien2k has some templates for fcc,bcc,simple-cubic and hcp BZ (These are
> "arbitrarily" chosen
> paths through the BZ) and of course if you have one of those symmetries,
> you can select the
> appropriate one and then "click the button".
>
> Alternatively you can choose "From xcrysden" (and "Click Create"), or you
> have to define
> the k-vector list manual. The Bilbao-site helps you to "see" the BZ and
> coordinates and names
> of special k-points.
>
>  I need to know one small information: on what basis the sequences of high
>> symmetry points of the Brillouin zones are chosen? I know that XCrysDen
>> would help to choose any sequence
>> we like; but, there often times in our system XCrysDen does not run! In
>> such situations we use the Brillouinzones from Bilbao Cryst Server
>> <http://www.cryst.ehu.es/cgi-**bin/cryst/programs/nph-table?**from=kv<http://www.cryst.ehu.es/cgi-bin/cryst/programs/nph-table?from=kv>>
>> option. This one automatically sets the sequence. I like to have more
>> understanding about how this is done.
>>
>> Please let me know any refence papers or we pages which could give me more
>> inputs to understand this.
>> Literature have many different schemes, but I do not know what is used in
>> Wien2k 11.1
>> Thanks.
>>
>> --
>> /K. Balamurugan
>> Pittsburgh, USA.
>> +1 412 961 5055/
>>
>>
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>>
>
> --
>
>                                      P.Blaha
> ------------------------------**------------------------------**
> --------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
> Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/**
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-- 
*K. Balamurugan
Pittsburgh, USA.
+1 412 961 5055*
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