[Wannier] MoS2 bands using Wannier

Aron Szabo szaboa at iis.ee.ethz.ch
Tue Jun 2 11:39:13 CEST 2015


If you have the same number of bands as Wannier function then the 
disentanglement is switched off by default. So as Yunpeng wrote, use the 
exclude_bands option. In your case, if you had 20 bands in the ab initio 
calculation, then you should use exclude_bands = 1-2;14-20
It has to be specified when generating the projections and the overlaps 
with the ab-initio code. During the wannierization this command has no 
effect as far as I know.
(You might still need to explicitly specify num_bands= 11 before doing 
the wannierization)

Aron

On 06/02/2015 05:04 AM, Yunpeng Wang wrote:
> to use the exclude_bands tag.
>
> On Mon, Jun 1, 2015 at 10:59 PM, Elio Physics <elio-physics at live.com 
> <mailto:elio-physics at live.com>> wrote:
>
>     Dear Aron,
>
>     Thanks for your help. I completely agree that MoS2 does not need
>     disentanglement contrary to graphene or Si for example; however I
>     have been having problems switching it off. How do you switch
>     disentanglement off? i tried by not specifying the windows;
>      Wannier still took disentanglement into consideration.. When I
>     tried not to specify the number of bands, disentanglement was only
>     done; however I got another error:
>
>     " param_read: mismatch in MoS2.eig
>     Error: examine the output/error file for details
>     "
>     I a not sure how to solve this. I have not specified nbands in any
>     of the scf, nscf or win files. Based on the input i provided in my
>     first e-mail could you please let me know how to change the input
>     so I would turn off disentanglement without further errors?
>
>     Thank you in advance
>
>     ------------------------------------------------------------------------
>     Date: Mon, 1 Jun 2015 10:44:19 +0200
>     From: szaboa at iis.ee.ethz.ch <mailto:szaboa at iis.ee.ethz.ch>
>     To: wannier at quantum-espresso.org <mailto:wannier at quantum-espresso.org>
>     Subject: Re: [Wannier] MoS2 bands using Wannier
>
>     Dear Elio,
>
>     try to exclude the bottommost two bands (that are of sulfur s
>     character) and use the Mo:l=2 S:l=1 projections to capture the
>     next 11 bands. The lowest 13 bands are not supposed to be
>     entangled with the higher ones, so you won't need to use the
>     disentanglement method at all. Also, make sure that the ab initio
>     calculation is converged. If it is a monolayer then you don't need
>     to sample the Brillouin zone along the z direction, but in the
>     in-plane direction I would suggest a higher, odd number of K
>     points, eg: 15x15x1 mesh.
>
>     Best,
>     Aron Szabo
>     IIS, ETH Zurich
>
>     On 06/01/2015 02:18 AM, Elio Physics wrote:
>
>
>
>         ------------------------------------------------------------------------
>         From: elio-physics at live.com <mailto:elio-physics at live.com>
>         To: yunpengwang85 at gmail.com <mailto:yunpengwang85 at gmail.com>
>         Subject: RE: [Wannier] MoS2 bands using Wannier
>         Date: Mon, 1 Jun 2015 03:17:47 +0300
>
>         Dear Wang,
>
>         I also used Mo:d and S:p as projections  but i still got the
>         same problem.
>
>         Regards
>
>         Elio
>         University of rondonia
>         Br
>
>         ------------------------------------------------------------------------
>         Date: Sun, 31 May 2015 20:15:01 -0400
>         Subject: Re: [Wannier] MoS2 bands using Wannier
>         From: yunpengwang85 at gmail.com <mailto:yunpengwang85 at gmail.com>
>         To: elio-physics at live.com <mailto:elio-physics at live.com>
>
>         The most important part in the WIN file is the projection. You
>         should use some reasonable projections. Random projections
>         would give you random things.
>
>         On Sun, May 31, 2015 at 8:05 PM, Elio Physics
>         <elio-physics at live.com <mailto:elio-physics at live.com>> wrote:
>
>             Dear All,
>
>             I am trying to obtain the band structure of MoS2 using
>             Wannier. However the bands I am obtaining are "wiggly" and
>             do not agree with the band structure using first principle
>             calculations. I believe that the problem lies in the
>             "disentanglement", projection functions parts. I tried
>             every combination but nothing seems to work. i would
>             appreciate any help in this matter.  The bands are
>             attached to this e-mail. The  .WIN file input  I am using is:
>
>             num_bands       =20
>              num_wann        =  11
>              num_iter        = 400
>             dis_froz_max=-1.8
>             dis_win_max=8.5
>              guiding_centres=true
>
>             ! SYSTEM
>
>
>             begin unit_cell_cart
>             bohr
>             5.8000000 0.0000000 0.0000000
>             -2.9000000 5.0229450 0.0000000
>             0.0000000 0.0000000 58.0000000
>             end unit_cell_cart
>
>             begin atoms_frac
>             Mo       0.222222300 0.636894700   0.250005200
>             S        0.722222300 0.348218800  -0.266580000
>             S        0.722222400 0.348219400   0.766574900
>
>             end atoms_frac
>
>             begin Projections
>             random
>             end Projections
>
>
>             begin kpoint_path
>             G 0.000000  0.000000  0.000000   X 0.3333333 0.3333333
>             0.0000000
>             X 0.3333333 0.3333333 0.0000000  Y 0.5000000 0.0000000
>             0.0000000
>             Y  0.5000000 0.0000000 0.0000000 G 0.0000000 0.0000000
>             0.000000
>             end kpoint_path
>
>
>             ! KPOINTS
>
>             mp_grid : 6 6 6
>
>             begin kpoints
>               0.00000000  0.00000000  0.00000000  4.629630e-03
>               0.00000000  0.00000000  0.16666667  4.629630e-03
>               0.00000000  0.00000000  0.33333333  4.629630e-03
>               0.00000000  0.00000000  0.50000000  4.629630e-03
>             ......
>
>
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>
>
>
>         -- 
>         --------------------------------------------------------
>         Yun-Peng Wang
>         Postdoctoral Associate
>         Department of Physics and the
>         Quantum Theory Project
>         University of Florida
>         ypwang at ufl.edu <mailto:ypwang at ufl.edu>
>
>
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>
> -- 
> --------------------------------------------------------
> Yun-Peng Wang
> Postdoctoral Associate
> Department of Physics and the
> Quantum Theory Project
> University of Florida
> ypwang at ufl.edu <mailto:ypwang at ufl.edu>
>
>
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