[QE-users] Fwd: [QE-user]Need of a dipole correction for a surface calculation

[ignacio lizana]

Dipole moment correction is needed when you have a periodic system, because
periodicity can create an artificial electrostatic potential. If you have
your sistem at the bottom of a supercell (periodic system) and the vacuum
space is ubicated at only one side of your system, the periodicity creates
vacuum space on both sides. With respect to emax, eopreg and edir
parameters, the most easy way to set these, is positionate your system at
the middle of the supercell and set emax:0.95, eopreg: 0.05 and edir:3
(z-axis), according to the tutorial provided before.
In order to know if it is necessary to correct the dipole moment. you
should run SCF calculations on both systems with dipole moment correction
and without this, having in mind advice in the tutorial.

It would be great If someone in this forum has more information related to
this.



El dom., 30 ago. 2020 a las 5:15, Yuvam Bhateja (<yuvamb16 at gmail.com>)
escribió:

> Thank you sir for the help.
>
> I actually watched this tutorial.
> It was very helpful.
>
> I have a doubt like, in tutorial, he is using a slab which has vacuum on
> both sides.
>
> In my case, it has only one side. Do I still need a dipole correction is
> my potential surface isn't flat in vacuum?
>
> And if so, what should be the variables emaxpos, etc.?
>
> From where should I start increasing my external electric field?
>
> In tutorial he started inside the bottom vacuum towards the top vacuum.
>
> Hope your advice will help me understand better and solve my problem.
>
> Regards
> Yuvam Bhateja
>
> On Sat, 29 Aug 2020, 10:58 pm ignacio lizana, <ignaciolizana1 at gmail.com>
> wrote:
>
>> Hi Yuvan Bhateja:
>>
>> I am a new QE user too, but this tutorial video helped me with a similar
>> problem (Dipole moment correction in a supercell). Links are attached:
>>
>> Part 1: https://www.youtube.com/watch?v=QzmX5P_lNXY
>> Part 2: https://www.youtube.com/watch?v=ES4kAK4jLfQ
>>
>> I hope this helps you.
>>
>> Regards
>>
>> El sáb., 29 ago. 2020 a las 11:02, Yuvam Bhateja (<yuvamb16 at gmail.com>)
>> escribió:
>>
>>> Can someone please take a look at this?
>>>
>>> I'll be highly glad.
>>>
>>> Regards
>>> Yuvam Bhateja
>>>
>>> ---------- Forwarded message ---------
>>> From: Yuvam Bhateja <yuvamb16 at gmail.com>
>>> Date: Fri, 28 Aug 2020, 1:04 pm
>>> Subject: [QE-user] Need of a dipole correction for a surface calculation
>>> To: Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>
>>>
>>>
>>> Hello everyone,
>>>
>>> I am new in the DFT and QE community and still learning.
>>> I want to know if I need a dipole correction for my heterostructure.
>>>
>>> I have a graphene sheet layered over my Cr2O3 unit cell with 10A of
>>> vacuum on top.
>>> I am aware that usually dipole correction is needed for slab calculation
>>> where there should be vacuum on both sides of the slab and if the potential
>>> isn't flat.
>>>
>>> But my system has vacuum only on one side and the bottom layer is fixed
>>> to replicate bulk structure.
>>> Can I use dipole correction in my system? and what should be the value
>>> for parameters like emaxpos, edir and eopreg?
>>>
>>> I am attaching my input file.
>>>
>>> Please can someone help me over this?
>>>
>>> Regards
>>> Yuvam Bhateja
>>> Bachelor of Technology
>>> E&Tc
>>> IIEST Shibpur
>>> India
>>>
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>>
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>
> _______________________________________________
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