[Pw_forum] Applying a perpendicular Electric Field
bsalmankurt at gmail.com
Fri Nov 20 15:56:08 CET 2015
Dear Dr. Thomas Brumme,
Thank you again. I never forget this :)
2015-11-20 16:51 GMT+02:00 Thomas Brumme <thomas.brumme at mpsd.mpg.de>:
> Dear Bahadır,
> the input file seems to be OK. Nevertheless, you always have to test in
> the end
> that no charge is spilling into the vacuum because the sawtooth function is
> creating an artificial potential minimum. Do this by plotting to total
> (pp.x, plot_num=1) for example as 3D data file and using average.x to
> over the in-plane directions. If charge is spilling the potential is not
> linear in the
> vacuum region or shows other weird behavior. In this case you have to
> the vacuum region in order to reduce the depth of the artificial minimum.
> on the other hand can lead (for too large electric fields) to a vacuum
> which is too small, i.e., leading to interactions between the repeated
> The wrong gap you get can be due to anything - your initial input file was
> wrong. The sawtooth within the slab itself is an unphysical situation.
> P.S.: You're using an ultrasoft pseudopotential. In such cases ecutrho
> needs to
> be larger than just 4 times ecutwfc. More like 10 times... Which is also
> stated in
> the documentation...
> On 11/20/2015 03:27 PM, Bahadır salmankurt wrote:
> Dear Dr. Thomas Brumme,
> Thank you for clear explanation.
> And also I have changed my input file. now, Is everything ok?
> tstress = .true.
> tprnfor = .true.
> pseudo_dir ='/home/hakan/tubitak/espresso-5.2.0/pseudo/',
> ! etot_conv_thr = 1.0E-4,
> ! forc_conv_thr = 1.0D-3,
> ! verbosity='high',
> nat= 2, ntyp=1,
> ecutwfc =30.0,
> * emaxpos=0.95,*
> 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..
> 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
> Pw_forum mailing list
> Pw_forum at pwscf.org
Sakarya University, TURKEY
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