[CP2K-user] [CP2K:14983] What are the default units of hartree potential and electric field in cp2k?

[Kaixuan Chen]

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
>>>
>>> -- 
>>> You received this message because you are subscribed to the Google 
>>> Groups "cp2k" group.
>>> To unsubscribe from this group and stop receiving emails from it, send 
>>> an email to cp... at googlegroups.com.
>>> To view this discussion on the web visit 
>>> https://groups.google.com/d/msgid/cp2k/dc6eef99-9c9e-4c32-a57e-0dbd4065fff3n%40googlegroups.com 
>>> <https://groups.google.com/d/msgid/cp2k/dc6eef99-9c9e-4c32-a57e-0dbd4065fff3n%40googlegroups.com?utm_medium=email&utm_source=footer>
>>> .
>>>
>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20210322/d6008edd/attachment.htm>