[Wien] Surface dipole of a metal

[sjalali at sci.ui.ac.ir]

  Dear Prof. Laurence Marks,
Thank you for your additional clarification. I understand that you are  
specifically interested in separating the dipole moment from the  
mean-inner potential component using the WIEN2k software. However, I  
must admit that I cannot fully comprehend this concept, as I believe  
that in the bulk of metal, the electric dipole moment should be zero  
due to Gauss's law. Nevertheless, at the surface, where the crystal  
symmetry is broken, and the environment differs from the bulk, the  
existence of a dipole moment becomes possible.

  Currently, I am not aware of a direct method within the WIEN2k  
package for separating the dipole moment from the mean-inner  
potential. However, there may exist alternative approaches or external  
tools that can be employed in conjunction with WIEN2k to achieve this  
desired separation.

  Warmest regards,
Saeid.

Quoting Laurence Marks <laurence.marks at gmail.com>:

> Dear Saeid,
>     
>    Thanks for the suggestion. One can certainly calculate a surface  
> dipole for an adsorbate using the method you suggest, subtracting  
> that for a clean surface from the adsorbed case.
>     
>    However, what I want is the dipole of just the metal, e.g. the  
> classic Lang-Kohn form https://doi.org/10.1103/PhysRevB.3.1215. I  
> want to separate the dipole from the mean-inner potential component.
>
>     --
> Professor Laurence Marks (Laurie)
> Department of Materials Science and Engineering, Northwestern University
> www.numis.northwestern.edu[1]
> "Research is to see what everybody else has seen, and to think what  
> nobody else has thought" Albert Szent-Györgyi
>
>          On Tue, Jun 6, 2023, 11:26 <sjalali at sci.ui.ac.ir> wrote:
>
>> _Dear Prof. Laurence Marks,
>> Hi,
>> Thank you for your inquiry. Calculating the surface dipole of a  
>> metal can be an interesting and challenging task. While I cannot  
>> provide a personal account of testing the DIPOLE option in AIM, I  
>> can suggest an approach that might be helpful.
>>
>> The surface dipole moment, denoted as $\mu$ in Debye, can be  
>> calculated using the Helmholtz equation:
>>
>> $\Delta\Phi = \frac{1}{2\pi\Theta}\frac{\mu}{A}$,
>>
>> where $\Delta\Phi$ is the work-function change in eV, $A$ is the  
>> area per ($1\times1$) surface unit cell in $\text{\AA}^2$, $\Theta$  
>> represents the adsorbate coverage in monolayers. The equation  
>> expressing the surface dipole moment is given by Eq. (4) of  Ref.  
>> [Physical Review B, 73, 165424 (2006)], see also Fig. 2 of this  
>> reference, where $\mu$ and $\Delta \Phi$ are shown as a function of  
>> coverage for O in the fcc-hollow site.
>>
>> The work function, as the difference between the electrostatic  
>> potential in the middle of the vacuum and the Fermi energy of the  
>> slab, can be calculated using Eq. (1) of  Ref.  
>> [http://dx.doi.org/10.1016/j.commatsci.2009.09.027], you would also  
>> see Fig. 2 of [http://dx.doi.org/10.1063/1.3486216].
>>
>> I hope this suggestion is helpful to you. Should you have any  
>> further questions or require more specific guidance, please feel  
>> free to ask.
>> Good luck with your research!
>> Warmest Regards,
>> Saeid_
>>
>>
>> _ _
>>
>>
>>
>> _Quoting Laurence Marks <laurence.marks at gmail.com>:_
>>
>>> _I wonder if anyone has a good suggestion for calculating the  
>>> surface dipole of a metal (e.g. Al). The DIPOLE option in aim  
>>> might do it, although I have no idea if that works. If anyone has  
>>> tested it please let me know; alternatively, if you have an  
>>> inspiration on how to test it against a calibrant that would be  
>>> informative._
>>>          _ _
>>>          _I am always hopeful..._
>>>          _ _
>>> _--_
>>>                    _Professor Laurence Marks (Laurie)
>>> Department of Materials Science and Engineering
>>> Northwestern University
>>> www.numis.northwestern.edu[1]
>>> "Research is to see what everybody else has seen, and to think  
>>> what nobody else has thought", Albert Szent-Györgyi_
>>
>>
>>  
>>
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Links:
------
[1] http://www.numis.northwestern.edu
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