[QE-users] E-field units inconsistent

[Lorenzo Bastonero]

Dear Joseph,

In Ry a.u. the electric charge is sqrt(2), thus the units are correct.

Best,
Lorenzo

********************************
Lorenzo Bastonero

PhD Student
U Bremen Excellence Chair,
Bremen Center for Computational Materials Science,
and MAPEX Center for Materials and Processes

University of Bremen
Faculty of Production Engineering
TAB-Building, Room 3.32
Am Fallturm 1
28359 Bremen, DE

http://www.hmi.uni-bremen.de/

> Il giorno 14 feb 2023, alle ore 23:43, Joseph Frimpong <gy1906 at wayne.edu> ha scritto:
> 
> Dear Users and Developers,
> 
> I need clarifications on the finite e-field conversion factor for 1 a.u found on the input file description at https://www.quantum-espresso.org/Doc/INPUT_PW.html <https://www.quantum-espresso.org/Doc/INPUT_PW.html#idm840> and in the source code at $QEDIR/PW/src/extfield.f90.
>  
> Reading the input file description online: under “efield”, says in Ry a.u.; 1 a.u. = 36.3609*10^10 V/m
>  
> We know E-field in a.u. is 5.14220674763(78)×10^11 V⋅m−1 from https://en.wikipedia.org/wiki/Hartree_atomic_units <https://en.wikipedia.org/wiki/Hartree_atomic_units>; which means in Ry a.u., it should be 51.422/2 = 25.711, but the 36.3609 is actually 51.422/sqrt(2).
>  
> In the source code: $QEDIR/PW/src/extfield.f90, line #38, in the variable “eamp”, the comment says “(1 a.u. = 51.44 10^11 V/m)” which matches the Wikipedia result but not the INPUT_PW webpage.
> 
> Which one is correct?  Can someone please resolve this confusion?
>  
> Thanks for your time.
> 
> -----------------------------------------
> Joseph Frimpong
> Graduate Research Assistant 
> Department of Chemistry
> Wayne State University
> 
> 
> -----------------------------------------
> Joseph Frimpong
> Graduate Research Assistant 
> Liu's Group
> Department of Chemistry
> Wayne State University
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