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[Jedo <jedokim@umich.edu>]

Hi Emmanuel,

The coordinates that I put in the electronic band calculation were ok. I 
used that for cell optimization, and now I see why it took such a long 
time.  The inputs were for the band structure calculation was

            -1.0819076730E-07  3.1237498018E-02 -1.0819076730E-07
             2.5000000000E-01  2.8127547637E-01  2.5000000000E-01
             5.0001031065E-01  5.3126896924E-01 -1.0310652951E-05
            -1.0310652951E-05  5.3126896924E-01  5.0001031065E-01
             5.0000010819E-01  3.1237498018E-02  5.0000010819E-01
             7.5000000000E-01  7.8123269824E-01  2.5000000000E-01
             2.5000000000E-01  7.8123269824E-01  7.5000000000E-01
             7.5000000000E-01  2.8124619263E-01  7.5000000000E-01

so it should be ok right?

Thanks!!


Jedo


Emmanuel Arras wrote:
> Actually, your input file for the conventionnal cell is wrong:
> xred
>     0.0 0.0 0.0
>     1/4 1/4 1/4
>     1/2 1/2 0.0
>     0.0 1/2 1/2
>     1/2 0.0 1/2
>     3/4 3/4 1/4
>     1/4 3/4 3/4
>     3/4*_ 1/2_* 3/4
>
> 1/2 in the last line should be 1/4
>
> Then what does it give?
>
>
> Emmanuel
>
>
>
> Jedo a écrit :
> > Hi there,
> >
> > Hmm.. If I'm understanding this right, whatever the cell size is, the 
> > band structure at the Gamma point, (0 0 0) should be the same right?
> > For primitive cell, I have the following points for band structure at 
> > (0 0 0)
> >
> > kpt#  21, nband= 16, wtk=  1.00000, kpt=  0.0000  0.0000  0.0000 
> > (reduced coord)
> >  -6.19323   5.85746   5.85746   5.85746   8.37713   8.37713   
> > 8.37713   9.00292
> >  13.48225  13.60932  13.60932  16.99403  16.99403  16.99403  
> > 20.87852  28.80835
> >
> > For conventional cell, I have the following
> >
> >
> > kpt#  21, nband= 32, wtk=  1.00000, kpt=  0.0000  0.0000  0.0000 
> > (reduced coord)
> >  -6.16413  -1.94700  -1.94697  -1.94688  -1.94662  -1.94648  
> > -1.94640   3.03807
> >   3.03808   3.03813   3.03826   3.03833   3.03833   5.94579   
> > 5.94595   5.94612
> >   6.51126   6.51137   6.51168   6.51184   6.51207   6.51211   
> > 8.46920   8.46929
> >   8.46939   9.18951  13.60797  13.70326  13.70326  16.00834  
> > 16.00841  16.00857
> >
> >
> > I have included more bands.
> > However, the primitive cell band gap is between 5.85746 eV and 
> > 8.37713 eV. There are no bands between them. But for conventional 
> > cell, I have 6.51126 eV band between the two band gap. Is this normal 
> > when I use the conventional cell?
> > Thanks.
> >
> >
> > Jedo
> >
> >
> > Emmanuel Arras wrote:
> > > Pardon my naive question, but have you "folded" your results? That 
> > > is, band structure performed on a bigger cell than the primitive one 
> > > will have more bands in a smaller BZ. So, if you want to compare the 
> > > results with the primitive cell, you have to "fold" them.
> > > hopping I made myself clear...
> > >
> > > Emmanuel
> > >
> > >
> > > ธนูสิทธิ์ บุรินทร์ประโคน a écrit :
> > > > Dear all
> > > >
> > > > I have in mind the same question as Jedo's.
> > > >
> > > > I think the initail results of band calculations would look 
> > > > different between the primitive cell and the conventional cell. 
> > > > This is because the two cells have the Brillouin zones of different 
> > > > sizes and shapes so that the k-points sampling used in the band 
> > > > calculation are different. However, since we perform the band 
> > > > calculation for the same crystal, both results should lead to 
> > > > identical intepretation.  The problem is how?  Is there other 
> > > > points I am missing?
> > > > All comments or suggestions will be greatly appreciated.
> > > >  
> > > >
> > > > Regards,
> > > >
> > > > Thanusit Burinprakhon
> > > >
> > > >  
> > > >
> > > >
> > > >
> > > >
> > > > */On November 23, 2009 10:39:13 AM ICT, "Jedo" <jedokim@umich.edu> 
> > > > wrote:/*
> > > >
> > > >     Hi all,
> > > >
> > > >     I am trying to compare if I get the same result for primitive
> > > >     cells and
> > > >     conventional cell when performing the electronic band structure
> > > >     calculation. I may be totally wrong because I am just starting the
> > > >     calculation. I am using two different structures, one for
> > > >     conventional
> > > >     cell and one for primitive cell. Shouldn't the following
> > > >     structure give
> > > >     me the same results? Not sure why I'm getting a totally different
> > > >     band
> > > >     structures. Please let me know if I'm just stupid. :) Thanks!!
> > > >
> > > >     Primitive cell
> > > >
> > > >     #Definition of the unit cell
> > > >     -> acell 3*10.217 # This is equivalent to 10.217 10.217 10.217
> > > >     -> rprim 0.0 0.5 0.5 # FCC primitive vectors (to be scaled by 
> > > > acell)
> > > >     -> 0.5 0.0 0.5
> > > >     -> 0.5 0.5 0.0
> > > >     ->
> > > >     -> #Definition of the atom types
> > > >     -> ntypat 1 # There is only one type of atom
> > > >     -> znucl 14 # The keyword "znucl" refers to the atomic number 
> > > > of the
> > > >     -> # possible type(s) of atom. The pseudopotential(s)
> > > >     -> # mentioned in the "files" file must correspond
> > > >     -> # to the type(s) of atom. Here, the only type is
> > > >     -> Silicon.
> > > >     ->
> > > >     ->
> > > >     -> #Definition of the atoms
> > > >     -> natom 2 # There are two atoms
> > > >     -> typat 1 1 # They both are of type 1, that is, Silicon.
> > > >     -> xred # This keyword indicate that the location of the atoms
> > > >     -> # will follow, one triplet of number for each atom
> > > >     -> 0.0 0.0 0.0 # Triplet giving the REDUCED coordinate of atom 1.
> > > >     -> 1/4 1/4 1/4 # Triplet giving the REDUCED coordinate of atom 2.
> > > >
> > > >
> > > >
> > > >
> > > >     Conventional Cell
> > > >
> > > >     #Definition of the unit cell
> > > >     acell 3*10.217 # This is equivalent to 10.18 10.18 10.18
> > > >     rprim 1.0 0.0 0.0 # FCC primitive vectors (to be scaled by acell)
> > > >     0.0 1.0 0.0
> > > >     0.0 0.0 1.0
> > > >
> > > >     #Definition of the atom types
> > > >     ntypat 1 # There is only one type of atom
> > > >     znucl 14 # The keyword "znucl" refers to the atomic number of the
> > > >     # possible type(s) of atom. The pseudopotential(s)
> > > >     # mentioned in the "files" file must correspond
> > > >     # to the type(s) of atom. Here, the only type is Silicon.
> > > >
> > > >
> > > >     #Definition of the atoms
> > > >     natom 8 # There are two atoms
> > > >     typat 1 1 1 1 1 1 1 1 # They both are of type 1, that is, Silicon.
> > > >     xred # This keyword indicate that the location of the atoms
> > > >     # will follow, one triplet of number for each atom
> > > >     0.0 0.0 0.0
> > > >     1/4 1/4 1/4
> > > >     1/2 1/2 0.0
> > > >     0.0 1/2 1/2
> > > >     1/2 0.0 1/2
> > > >     3/4 3/4 1/4
> > > >     1/4 3/4 3/4
> > > >     3/4 1/2 3/4
> > > >
> > > >
> > > >     --     ================================
> > > >     Jedo Kim,
> > > >     Heat Transfer Physics Laboratory
> > > >     2350 Hayward, 2186 GG Brown Bldg.
> > > >     University of Michigan, Ann Arbor, MI 48109-2143
> > > >     Email: jedokim@umich.edu, jdzbox@hotmail.com
> > > >     Tel: 734-764-3487 (o); 734-276-8370 (cell)
> > > >     ================================
> > >
> > > --
> > > Emmanuel ARRAS
> > > L_Sim (Laboratoire de Simulation Atomistique)
> > > SP2M / INAC
> > > CEA Grenoble
> > > tel : 00 33 (0)4 387 86862
> > >   
>
> --
> Emmanuel ARRAS
> L_Sim (Laboratoire de Simulation Atomistique)
> SP2M / INAC
> CEA Grenoble
> tel : 00 33 (0)4 387 86862
>   

--
================================
Jedo Kim, 
Heat Transfer Physics Laboratory
2350 Hayward, 2186 GG Brown Bldg.
University of Michigan, Ann Arbor, MI 48109-2143
Email: jedokim@umich.edu, jdzbox@hotmail.com
Tel: 734-764-3487 (o);  734-276-8370 (cell)
================================