[Wien] Symmetry pts in Brillouin zone
Peter Blaha
pblaha at theochem.tuwien.ac.at
Fri Sep 16 07:48:31 CEST 2011
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>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>> 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>/
>
>
> _________________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.__at <mailto:Wien at zeus.theochem.tuwien.ac.at>
> http://zeus.theochem.tuwien.__ac.at/mailman/listinfo/wien <http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien>
>
>
> --
>
> P.Blaha
> ------------------------------__------------------------------__--------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-15671 <tel:%2B43-1-58801-15671> FAX: +43-1-58801-15698 <tel:%2B43-1-58801-15698>
> Email: blaha at theochem.tuwien.ac.at <mailto:blaha at theochem.tuwien.ac.at> WWW: http://info.tuwien.ac.at/__theochem/ <http://info.tuwien.ac.at/theochem/>
> ------------------------------__------------------------------__--------------
> _________________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.__at <mailto:Wien at zeus.theochem.tuwien.ac.at>
> http://zeus.theochem.tuwien.__ac.at/mailman/listinfo/wien <http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien>
>
>
>
>
> --
> /K. Balamurugan
> Pittsburgh, USA.
> +1 412 961 5055 <tel:%2B1%20412%20961%205055>/
>
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
--
-----------------------------------------
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
-----------------------------------------
More information about the Wien
mailing list