The manual says that when applying an homogeneous electric field via EFIELD_PEAD the field should be specified in units eV/Å.
This is rather confusing. Various pages on the web suggest the unit is indeed V/Å multiplied by the electron charge e. But that is not a field unit, as e comes with coulomb units, so eV/Å should be proportional to CV/Å. That looks like a force unit of something like 1.0e-10*N. Not a field strength.
Anyway, assuming the above is correct, would I indeed specify EFIELD_PEAD of about 6.2e18 to get an applied field of 1 V/Å?
External field units
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Re: External field units
Just in case anyone stumbles upon this post when having the same question.
Indeed the EFIELD_PEAD should be understood as the force that an electron will feel when placed in the electric field (this was corrected in the wiki).
Consider the following relations
E = F*d (2)
E = q*V (3)
with
E -> Energy
V -> Potential (Energy as well)
q -> Electron charge
F -> Force
d -> length
this means that
F=q*V/d
Then q*V has dimensions of energy which in VASP means eV.
The unit of length in VASP is Å so F has units of eV/Å.
See related posts:
forum/viewtopic.php?f=3&t=17653
forum/viewtopic.php?f=4&p=22393
Indeed the EFIELD_PEAD should be understood as the force that an electron will feel when placed in the electric field (this was corrected in the wiki).
Consider the following relations
E = F*d (2)
E = q*V (3)
with
E -> Energy
V -> Potential (Energy as well)
q -> Electron charge
F -> Force
d -> length
this means that
F=q*V/d
Then q*V has dimensions of energy which in VASP means eV.
The unit of length in VASP is Å so F has units of eV/Å.
See related posts:
forum/viewtopic.php?f=3&t=17653
forum/viewtopic.php?f=4&p=22393