[CP2K-user] [CP2K:21917] Re: Planar average potential along Z in &EXTERNAL_POTENTIAL

[Ravi Kumar]

Hi xuan Garrett,

Thanks a lot for the suggestion,  it works well now.

I have one more question for clarification:
&EXTERNAL_POTENTIAL
    FUNCTION (A/B)*Z
    VALUES [eV] 0.2 [angstrom] 1.0
    PARAMETERS A B
&END EXTERNAL_POTENTIAL

If I understand the notation correctly, the applied potential corresponds 
to *0.2 V/Å* in the z-direction, right?

Best,
Ravi

On Friday, October 24, 2025 at 6:30:17 PM UTC+9 xuan Garrett wrote:

> Hi，Ravi，
> Yes，the problem is that the potential applied by efield is not written in 
> V_hartree，but in &PRINT External_field cube. Then you should connect the 
> two cubes to obtain the saw-tooth potential.
> Best regards
> Xuan
>
> Ravi Kumar <ravikum... at gmail.com>于2025年10月24日 周五17:23写道：
>
>> Hi xuan Garrett,
>>
>> I am also interested in applying a saw-tooth potential, as done in VASP, 
>> using CP2K and obtaining results similar to yours. 
>> Were you able to achieve the expected results with CP2K?
>>
>> Best,
>> Ravi
>>
>> On Monday, March 3, 2025 at 4:50:18 AM UTC+9 Quentin Pessemesse wrote:
>>
>>> I am not sure if this line is correct:
>>> VALUES [eV] 0.2 [angstrom] 1.0 
>>> According to the manual, you should define units in another line with 
>>> the keyword "UNITS eV angstrom". Maybe either or both of your values is not 
>>> being read correctly.
>>> Tell me if that works :)
>>> Best,
>>> Quentin
>>> Le mercredi 26 février 2025 à 06:11:46 UTC+1, xuan Garrett a écrit :
>>>
>>>> Dear cp2k,
>>>>
>>>> I am trying to deal with the planar average potential under static 
>>>> electric field, which is realized by &EXTERNAL_POTENTIAL in &DFT section, 
>>>> and the dipole correction is switched on:
>>>> SURFACE_DIPOLE_CORRECTION T
>>>> SURF_DIP_DIR Z
>>>> &EXTERNAL_POTENTIAL
>>>>     FUNCTION (A/B)*Z
>>>>     VALUES [eV] 0.2 [angstrom] 1.0
>>>>     PARAMETERS A B
>>>> &END EXTERNAL_POTENTIAL 
>>>>
>>>> However, by checking the hartree.cube in the field of 0.2 eV/Angstrom, 
>>>> the saw-tooth potential is not observable, while in VASP, the LOCPOT 
>>>> displays such saw-tooth potential. 
>>>>
>>>> So, if there is the problem with such condition in CP2K? How to deal 
>>>> with this?
>>>> [image: image.png][image: image.png]
>>>>
>>>> Best regards,
>>>> Xuan
>>>>
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