[QE-users] dipole correction with assume isolated ESM

[Minoru Otani]

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
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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/
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> 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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