[Wien] Symmetry pts in Brillouin zone
J. K. Balamurugan
albertbalagan at gmail.com
Fri Sep 16 16:09:30 CEST 2011
Dear Peter sir,
Thanks once again. As long as nothing comes wrong, I think, that will be OK
for me. I also hope as time goes I would learn to define
the k-vector list manually.
Thank you.
On Fri, Sep 16, 2011 at 1:48 AM, Peter Blaha
<pblaha at theochem.tuwien.ac.at>wrote:
> Yes, w2web reads the crystal lattice (P, B, F, H) and takes automatically
> the corresponding template.
>
> However, w2web does not take into account the spacegroup (symmetry) and
> cannot distinguish between eg. a "cubic P" and a "tetragonal P" lattice,
> but uses always the same template (for a cubic case).
> While in this way it will not make anything "wrong", but your bandstructure
> will eventually be shown not in (all) interesting directions.
>
> Am 16.09.2011 04:49, schrieb 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.at <mailto:pblaha at theochem.**tuwien.ac.at<pblaha at theochem.tuwien.ac.at>>p>
>> 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><
>> 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 <tel:%2B1%20412%20961%205055>/
>>
>>
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>>
>>
>> --
>>
>> P.Blaha
>> ------------------------------**__----------------------------**
>> --__--------------
>> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
>> Phone: +43-1-58801-15671 <tel:%2B43-1-58801-15671> FAX:
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>>
>>
>>
>> --
>> /K. Balamurugan
>> Pittsburgh, USA.
>> +1 412 961 5055 <tel:%2B1%20412%20961%205055>/
>>
>>
>>
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>>
>
> --
> ------------------------------**-----------
> Peter Blaha
> Inst. Materials Chemistry, TU Vienna
> Getreidemarkt 9, A-1060 Vienna, Austria
> Tel: +43-1-5880115671
> Fax: +43-1-5880115698
> email: pblaha at theochem.tuwien.ac.at
> ------------------------------**-----------
>
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>
--
*K. Balamurugan
Pittsburgh, USA.
+1 412 961 5055*
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