[CP2K-user] [CP2K:16413] Re: surface dipole correction:applicability/universality

[Marcella Iannuzzi]

Dear Victor 

The importance of the dipole correction depends on the electrostatic 
properties of the system. 
For instance in order to determine the workfunction from an asymmetric slab 
it is needed. 
On the other hand, for electrostatic ally symmetric system has no effect. 
Just compute energy and forces  with and without dipole correction to 
estimate its contribution for the specific system of interest.

Regards 
Marcella

On Tuesday, December 28, 2021 at 12:46:03 PM UTC+1 volk... at gmail.com wrote:

> Dear users and developers
> I wish to ask if this command
>
> SURFACE_DIPOLE_CORRECTION T
> SURF_DIP_DIR Z 
>
> Is this a universal MUST whenever we model ANY surface
> under PERIODIC XYZ?
> (I assume, this is not important under PERIODIC XY.)
>
> May I state that
> this is important for a metal surface (electronic delocalizations)
> where an adsorbed molecule (on the top)
> is symmetric in respect to X and Y 
> but not in respect to Z: like, OH anion under the vertical orientation?
>
> How important 
> SURFACE_DIPOLE_CORRECTION T
> should be if one would model systems like
> 2-3 layered graphite, 
> where the layers are well separated and barely "feel" each other (see 
> attached),
> or
> 2 layer silica with a disordered water cluster at the top,
> hence, there is no obvious symmetry and, due to the nature of atoms, 
> charges are rather localized (see attached).
>
> This is about, how universal is this article
> https://journals.aps.org/prb/abstract/10.1103/PhysRevB.59.12301 
> in the applications as programmed by cp2k.
>
> Thank you.
>
> Happy 2022 for every cp2k
> :-)
>
> Victor
>
>
>
>

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