[Pw_forum] Applying a perpendicular Electric Field

[Thomas Brumme]

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 list
> Pw_forum at pwscf.org
> http://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

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20151120/167dc441/attachment.html>