[Pw_forum] Are the units of the "efield" tag in the PW.x and CP.x codes different?

[S. Sanchez]

Dear all,

I have a question regarding the units of "finite electric fields" reported
in the input webpage of the PW.x code:

http://www.quantum-espresso.org/input-syntax/INPUT_PW.html

For example, in that webpage, the "eamp" tag reports the units of the
electric field in "Hartree" (51.4220632*10^10 V/m). This value for the
atomic units of the electric field makes complete sense; however, I do not
quite understand the units reported for "efield" tag.

For example, I understand the fact that the value of the "efield" tag should
be smaller than that of "eamp" tag; indeed, the value of the "finite
electric field" appears to be that of the "eamp" tag divided by the square
root of 2. That is: (51.4221*10^10 V/m)/SQRT(2)=36.3609*10^10 V/m.

What I do not understand is the fact that the label "efiled" in the
INPUT_PW.html webpage reports the following information:
Amplitude of the finite electric field (in Ry a.u.; 1 a.u. = 36.3609*10^10
V/m)

If I follow the above expression, i.e., (51.4221*10^10
V/m)/SQRT(2)=36.3609*10^10 V/m, the units of the "finite electric field"
should be Hartrees and not in Rydbergs, right?

Also, in the INPUT_CP.html webpage, the same label "efield" reports the
following:
Amplitude of the finite electric field (in a.u.; 1 a.u. = 36.3609*10^10
V/m); where, one assumes a.u. to be equal to Hartree.

So, I would like to know if the units of the "finite electric field" in the
PW.x code are given in Hartrees or in Rydbergs?

Thanks a lot for your help,
S. Sanchez
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