[CP2K-user] [CP2K:21924] Re: Planar average potential along Z in &EXTERNAL_POTENTIAL

[Ravi Kumar]

Hi Xuan,

I am not a QE user, but I have QE input file tags applying the static field

&control
calculation = 'scf'
prefix='C60onW100Lz6z01Ez001DC',
pseudo_dir = './',
outdir='./',
verbosity='high'
disk_io='low'
wf_collect=.true.
tefield = .true.
dipfield = .true.
/
&system
ibrav=  0,
nat=  140,
ntyp=   2,
A = 12.66088228,
ecutwfc =50.0,
ecutrho=475.0,
occupations='smearing',
smearing='m-p',
degauss=0.01
edir = 3,
emaxpos =0.80,
eopreg =0.90,
eamp = 0.009723452336177272
/
&electrons
   electron_maxstep = 400
   mixing_mode = 'plain'
   mixing_beta = 0.3
   conv_thr =  1.0d-8
/
CELL_PARAMETERS alat
 1.0  0.0  0.0
 0.0  1.0  0.0
 0.0  0.0  6.0
ATOMIC_SPECIES
 C   12.0107 C.pbe-n-kjpaw_psl.1.0.0.UPF
 W  183.84   W.pbe-spn-kjpaw_psl.1.0.0.UPF


Maybe this could be helpful for you.

Best,
Ravi

On Sat, Oct 25, 2025 at 8:58 PM xuan Garrett <xwgarrett at gmail.com> wrote:

> Hi Ravi，
>
> I may think that this static field is applied to simulate the
> Electric-field for electrocatalytic peformance，as revealed by Prof. Jens K.
> Norskov. And，how to set this function in QE？via pw.x
>
> Best regards，
> Xuan
>
>
> Ravi Kumar <ravikumar381709 at gmail.com>于2025年10月25日 周六13:27写道：
>
>> Hi Xuan,
>>
>> Thanks for the clarification.
>>
>> Yes, I also noticed that. I used  VALUES [eV] -0.2 [angstrom] 1.0  in
>> order to match with VASP/QE results.
>>
>> Thank you very much for your kind help.
>>
>> Best,
>> Ravi
>>
>>
>> On Sat, Oct 25, 2025 at 1:36 PM xuan Garrett <xwgarrett at gmail.com> wrote:
>>
>>> Hi，Ravi，
>>> Yes，you got it. This example is also provided in the official website
>>> from cp2k，that is the summer school by Prof. Matt. You can check it.
>>>
>>> Be aware that the direction of this static field is opposite to the
>>> traditional definition.
>>>
>>> Best regards，
>>> Xuan
>>>
>>> Ravi Kumar <ravikumar381709 at gmail.com>于2025年10月25日 周六11:37写道：
>>>
>>>>
>>>> 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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