[QE-users] dipole correction with assume isolated ESM

[Lucian D. Filip]

Dear Minoru,


Thank you very much for this clarification! I finally understand it now!

I have now tested my example and saw that there is no difference between 
a 10 angstrom vacuum region and a 20 vacuum region on either side of my 
slab. This is good news for me for my future calculations!


Best regards,


Lucian

On 15-Jul-24 4:59 AM, Minoru Otani wrote:
> Dear Lucian,
>
> By using esm_bc=bc1, you can obtain the desired results. In this case, dipole correction is not necessary.
>
> If you are calculating a system with no net dipole, the electrostatic potential on both sides will be flat and at the same level. On the other hand, if the system has a net dipole, the electrostatic potential on both sides will be flat, but the height of these flat regions will differ. This difference in height is related to the total dipole moment of the system.
>
> The former can be correctly calculated even with conventional periodic boundary conditions, while the latter can be naturally calculated using ESM (esm_bc=bc1).
>
> Best regards,
> Minoru
> -------------------------------------------------------------------------------------------------------
> Minoru Otani, Ph.D., Professor
> Center for Computational Sciences and Faculty of Pure and Applied Sciences,
> University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
> E-mail: otani at ccs.tsukuba.ac.jp
> Web: https://www2.ccs.tsukuba.ac.jp/public/otani/
> --------------------------------------------------------------------------------------------------------
>
>> On Jul 12, 2024, at 18:47, Lucian D. Filip <lucian.filip at infim.ro> wrote:
>>
>> Hello all,
>>
>> Is it possible to use the " assume_isolated='esm' ", with the " esm_bc='bc2' " flag for a slab geometry and perform the dipole correction? I have tried with 'esm_field=0' but it doesn't seem to enforce the 0 field in vacuum. Rather it just performs a regular scf calculation with no applied field.
>>
>> I know about the '2D' option but that adds other complications because if I increase the slab thickness, the vacuum region becomes really big in order to ensure that the Coulombian cutoff is not too close to the slab to influence the slab.
>>
>> Is there a way to enforce a zero field  in the vacuum region with ESM?
>>
>>
>> Regards,
>>
>>
>> Lucian
>>
>> -- 
>> Dr. Lucian Dragos Filip
>> National Institute of Materials Physics
>> Atomistilor str. 405A, PO Box MG. 7
>> Magurele, 077125
>> Bucharest, Romania
>> E-mail: lucian.filip at infim.ro
>> Website: https://lucianfilip.wordpress.com/
>>
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> _______________________________________________
> The Quantum ESPRESSO community stands by the Ukrainian
> people and expresses its concerns about the devastating
> effects that the Russian military offensive has on their
> country and on the free and peaceful scientific, cultural,
> and economic cooperation amongst peoples
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users

-- 
Dr. Lucian Dragos Filip
National Institute of Materials Physics
Atomistilor str. 405A, PO Box MG. 7
Magurele, 077125
Bucharest, Romania
E-mail: lucian.filip at infim.ro
Website: https://lucianfilip.wordpress.com/