[QE-users] Dipole correction: should there be a "dip" in the electrostatic potential?

[Christoph Wolf]

Hi Thomas,

I am using indeed 6.2 compiled with the new xml, I should have checked the
bugs first... since it is on the cluster I cannot re-compile but I will
forward the information to the cluster people!

Thank you for bringing this to my attention, this is *really* good to know!

Best,
Chris

On Fri, May 18, 2018 at 1:42 PM, Thomas Brumme <thomas.brumme at uni-leipzig.de
> wrote:

> Dear Christoph,
>
> which version of QE are you using? Was it compiled with the old XML format
> or the new one?
> The new XML format had a bug in the way the input related to the dipole
> correction was saved.
> This was solved about a month ago:
>
> https://gitlab.com/QEF/q-e/commit/81a946e15b80972f629c88e47e2545596350f31c
>
> see also the related issue (closed)
>
> https://gitlab.com/QEF/q-e/issues/5
>
> Maybe your problem is due to this. If you use 6.2.1 either download the
> develop branch or
> compile using the old XML implementation.
>
> Regards
>
> Thomas
>
>
> On 18.05.2018 12:50, Christoph Wolf wrote:
>
> Dear all,
>
> I am (again...) fighting with the dipole correction. I have a system
> consisting of Ag and MgO centered in the cell around z=0.5
>
> ATOMIC_POSITIONS (crystal)
> Ag       0.000000000   0.000000000   0.323271580
> Ag       0.000000000   0.500000000   0.385512833
> ....
> Mg      -0.000000000   0.000000000   0.721978968
> O        0.500000000   0.000000000   0.723372273
> O       -0.000000000   0.500000000   0.723371161
> Mg       0.500000000   0.500000000   0.721975961
>
> Then I apply tefield and dipfield with
>
>   eamp        = 0.00
>   edir        = 3
>   emaxpos     = 0.95
>   eopreg      = 0.10
>
> which means my system has no discontinuity anywhere in the slab and the
> field is "physical" between 0.95+0.1-1=0.05 and 0.95 of the z direction.
>
> The SCF cycle converges but the pot_num=11 never becomes horizontal,
> rather it has a very small slope. I tried to increase the dipole length to
> see if that makes a difference but apparently it does not help either. With
> above input the potential amplitude at scf convergence is
>
>      Adding external electric field
>
>      Computed dipole along edir(3) :
>         Elec. dipole          0.4894 Ry au,          1.2440 Debye
>         Ion. dipole           0.4902 Ry au,          1.2460 Debye
>         Dipole                0.2274 Ry au,          0.5779 Debye
>         Dipole field          0.0008 Ry au,
>
>         Potential amp.       -0.0855 Ry
>         Total length         55.5874 bohr
>
>
> Is there a scenario where the dipole correction could fail if the
> potential is "almost flat" in the vacuum region? If I run the same with
> VASP I get a small "jump" in the potential making it flat in the vacuum
> region, so I was wondering why this does not happen (probably different
> approach in PWSCF)?
>
> Input and resulting potential is attached - any help is welcome!
>
> Thanks in advance and with best wishes,
> Chris
> --
> Postdoctoral Researcher
> Center for Quantum Nanoscience, Institute for Basic Science
> Ewha Womans University, Seoul, South Korea
>
>
> _______________________________________________
> users mailing listusers at lists.quantum-espresso.orghttps://lists.quantum-espresso.org/mailman/listinfo/users
>
>
> --
> Dr. rer. nat. Thomas Brumme
> Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry
> Leipzig University
> Phillipp-Rosenthal-Strasse 31
> 04103 Leipzig
>
> Tel:  +49 (0)341 97 36456
>
> email: thomas.brumme at uni-leipzig.de
>
>


-- 
Postdoctoral Researcher
Center for Quantum Nanoscience, Institute for Basic Science
Ewha Womans University, Seoul, South Korea
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20180518/47bc74c6/attachment.html>