[CP2K-user] [CP2K:14983] What are the default units of hartree potential and electric field in cp2k?
Kaixuan Chen
kaix... at gmail.com
Mon Mar 22 20:34:27 UTC 2021
Dear Fangyong,
Thank you very much for the response. The units for the numbers of the cube
files (both potential and electric field) is exactly what I want to know.
They are not stated, neither in the cp2k manual nor in the cube files. So I
try to treat the numbers in a.u. units. For example, the electric field
cube file shows that at some positions, the number is 10 hartree/e/bohr if
the a.u. unit is the correct one. I think it is really huge for electric
field, isn't it?
By the way, when I mean 50000 MV/cm, I think it is equal to 50000 (10E6
V)/(10E8 Angstrom) = 500 V/Angstrom.
Because 1 hartree/e/bohr = 5142.20652 MV/cm, correct?
Any suggestion on what is the default unit?
Best,
Kai
在2021年3月22日星期一 UTC-7 下午12:03:03<fy... at gmail.com> 写道:
> Hi, Kai,
>
> I think you mean 5GV/cm = 500 V/Angstrom.
>
> I think you may need to do integration to obtain the electric field,
> because it is a cube file, so what is the unit for the numbers
> of your cube file?
>
> Fangyong
>
> On Mon, Mar 22, 2021 at 2:25 PM Fangyong Yan <fy... at gmail.com> wrote:
>
>> Hi, Kai,
>>
>> 50000 MV/cm = 50 V / (10E8) Angstrom = 5E-7 V/Angstrom, which is a very
>> very small electric field.
>>
>> Best,
>>
>> Fangyong
>>
>> On Mon, Mar 22, 2021 at 1:07 PM Kaixuan Chen <ka... at gmail.com> wrote:
>>
>>>
>>> Dear all,
>>> I have generated the cube files of hartree potential (CP2K_INPUT
>>> <https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT.html> / FORCE_EVAL
>>> <https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT/FORCE_EVAL.html> /
>>> DFT
>>> <https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT/FORCE_EVAL/DFT.html>
>>> / PRINT
>>> <https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/PRINT.html>
>>> / V_HARTREE_CUBE
>>> <https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/PRINT/V_HARTREE_CUBE.html>)
>>> and electric field (CP2K_INPUT
>>> <https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT.html> / FORCE_EVAL
>>> <https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT/FORCE_EVAL.html> /
>>> DFT
>>> <https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT/FORCE_EVAL/DFT.html>
>>> / PRINT
>>> <https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/PRINT.html>
>>> / EFIELD_CUBE
>>> <https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/PRINT/EFIELD_CUBE.html>)
>>> from cp2k. I don't see an explicit description on the units that are used
>>> in these cube files. If I take the a.u. as the default unit (hartree/e for
>>> potential, and hartree/e/bohr for electric field), the value seems pretty
>>> large. For example, I study the single water molecule system. The largest
>>> electric field at some density grid is 10~15 hartree/e/bohr, that is,
>>> ~50000 MV/cm. Please correct me if I am wrong, but the value seems
>>> unreasonable to me.
>>> Any suggestion will be welcome, thanks in advance.
>>> Best,
>>> Kai
>>>
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>>>
>>
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