Units of EFIELD

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Units of EFIELD

#1 Post by rgarcia » Wed Nov 28, 2018 2:03 pm

Dear VASP developers,

According to your manual, the EFIELD tag is in eV/Å. Also the OUTCAR reports these units.

However, an electric field must have units of "V/Å", instead of "eV/Å"; otherwise, it will be an electric force instead of an electric field. The original contribution of Neugebauer and Scheffler (Phys. Rev. B 1992, 46, 16967) was in "V/m", which is consistent with "V/Å". Is it possible that there is a typo both in the VASP manual and in the OUTCAR?

Kind regards,

Rodrigo García-Muelas
Postdoc - Prof. López Group
Institute of Chemical Research of Catalonia (ICIQ)
Av. Països Catalans, 16. 43007. Tarragona, Spain.
Phone +34 977920200 (ext. 307)
rgarcia@iciq.es - http://www.iciq.es/

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Re: Units of EFIELD

#2 Post by merzuk.kaltak » Wed Nov 28, 2018 4:29 pm

Dear Rodrigo García-Muelas,

Thank you for pointing that out, the wiki entry might be confusing indeed.
For clarification:
EFIELD is the magnitude of the electric force field for a test charge q (F = q E) and is measured in eV/Angstrom.
We have changed the description on the website.

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