[Pw_forum] Applying a perpendicular Electric Field

[Bahadır salmankurt]

Dear Dr. Thomas Brumme,

Thank you for clear explanation.

And also I have changed my input file. now, Is everything ok?

****
&control
    calculation='scf'
    restart_mode='from_scratch',
    prefix='As',
    tstress = .true.
    tprnfor = .true.
    pseudo_dir ='/home/hakan/tubitak/espresso-5.2.0/pseudo/',
    outdir='/home/hakan/tubitak/As/efield/out/',
!           etot_conv_thr = 1.0E-4,
!           forc_conv_thr = 1.0D-3,
     wf_collect=.true.,
!     verbosity='high',
tefield=.true.
*dipfield=.true.*
 /
&system
nbnd=10,
    ibrav=0,celldm(1)=1.8897,
    nat= 2, ntyp=1,
    ecutwfc =30.0,
    ecutrho=120,
*  emaxpos=0.95,*
  eopreg=0.10,
  edir = 3,
 eamp = 0.0105,
   /
...

****

By the way, the difference is that  , when E field was applied under 5.00
V/nm ( eamp = 0.0097 au) E field in prb paper which I shared , the band gap
became about 0.80 eV. But I find this band gap under 10.5 V/nm (eamp=0.0205
au) E field ( I have used new input data).

what does the reason such a difference happen?

Thank you again..


2015-11-20 14:08 GMT+02:00 Thomas Brumme <thomas.brumme at mpsd.mpg.de>:

> Dear Bahadır,
>
> I haven't read the paper, so I don't know all the details, but looking at
> your input file I see
> a problem which might explain differences (by the way what kind of
> differences?)
>
> If you want to apply an electric field I think you should turn on the
> dipole correction
> otherwise your result will depend on the cell dimension in the
> non-periodic direction.
> See the paper by Bengtsson
> http://journals.aps.org/prb/abstract/10.1103/PhysRevB.59.12301
>
> Inputvariable 'dipfield'
>
> This related paper is also nice:
> http://journals.aps.org/prb/abstract/10.1103/PhysRevB.63.205426
>
> Furthermore, the maximum of the saw needs to be in the vacuum region, but
> in your
> input it is within the layer. Change emaxpos to something close to 0, or
> shift your
> coordinates to the origin with respect to z.
>
> Regards
>
> Thomas
>
>
> On 11/20/2015 12:54 PM, Bahadır salmankurt wrote:
>
> Dear All,
>
> I want to apply E field to the slab.
>
>  I have correctly obtained the band structure without E field same as they
> did (page - 3)
> http://journals.aps.org/prb/abstract/10.1103/PhysRevB.91.085423 . But The
> problem occur when I apply E field. For example, They obtained the band
> structure with nearly 0.5 eV band gap under 5.4 V/nm(  eamp = 0.0105, I
> guess)(page-8). But I  got  the results in both band structure and band
> gap, differently. I think I made a mistake. what is the mistate I did?
> Actually, I really dont know how to apply e field correctly.
>
>
> Input parameter are given below.
>
> Thanks for advice
>
> ***
> &control
>     calculation='scf'
>     restart_mode='from_scratch',
>     prefix='As',
>     tstress = .true.
>     tprnfor = .true.
>     pseudo_dir ='/home/hakan/tubitak/espresso-5.2.0/pseudo/',
>     outdir='/home/hakan/tubitak/As/efield/out/',
> !           etot_conv_thr = 1.0E-4,
> !           forc_conv_thr = 1.0D-3,
>      wf_collect=.true.,
> !     verbosity='high',
>  tefield=.true.,
>  /
> &system
> nbnd=10,
>     ibrav=0,celldm(1)=1.8897,
>     nat= 2, ntyp=1,
>     ecutwfc =30.0,
>     ecutrho=120,
>   emaxpos=0.50,
>   eopreg=0.10,
>   edir = 3,
>   eamp = 0.0105,
>    /
>  &electrons
>     conv_thr =  1.0d-10,
>     mixing_beta = 0.3,
>     electron_maxstep=1000,
>     mixing_mode='local-TF',
>  /
> !&ions
> !ion_dynamics='bfgs'
> !/
> !&cell
> !cell_dofree='2Dxy'
> !/
> CELL_PARAMETERS
> 3.598204297   0.000000000   0.000000000
> 1.799099198   3.116138270   0.000000000
> 0.000000000   0.000000000  18.0000
> ATOMIC_SPECIES
> As 74.921595 As.pbe-n-van.UPF
> ATOMIC_POSITIONS {crystal}
> As       0.333333326   0.333333330   0.558616161
> As       0.666666674   0.666666670   0.481383839
> K_POINTS {automatic}
> 31 31 1 0 0 0
>
> --
>
> Bahadır SALMANKURT
> PhD student
> Sakarya University, TURKEY
>
>
> _______________________________________________
> Pw_forum mailing listPw_forum at pwscf.orghttp://pwscf.org/mailman/listinfo/pw_forum
>
>
> --
> Dr. rer. nat. Thomas Brumme
> Max Planck Institute for the Structure and Dynamics of Matter
> Luruper Chaussee 149
> 22761 Hamburg
>
> Tel:  +49 (0)40 8998 6557
>
> email: Thomas.Brumme at mpsd.mpg.de
>
>
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>



-- 

Bahadır SALMANKURT
PhD student
Sakarya University, TURKEY
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