[Pw_forum] Unit of dielectric constant tensor

[Kun Yin]

Dear PWSCF users,
   I am doing the phonon calculation of MgO. Part of the output is

> -------------- Output of PWSCF ph.x -------------------------------------
>         Dielectric constant in cartesian axis
>
>         (        3.23010        0.00000        0.00000 )
>         (        0.00000        3.23010        0.00000 )
>         (        0.00000        0.00000        3.23010 )
>
>         Effective charges E-U in cartesian axis
>
>          atom     1
>         (        2.01867        0.00000        0.00000 )
>         (        0.00000        2.01867        0.00000 )
>         (        0.00000        0.00000        2.01867 )
>          atom     2
>         (       -2.03905        0.00000        0.00000 )
>         (        0.00000       -2.03905        0.00000 )
>         (        0.00000        0.00000       -2.03905 )
> ---------------------------------------------------------------------------

   My question is what are the units of the above physical quantities, the 
dielectric constant and effective charge, in PWSCF?
   Any help will be appreciated.

Regards,
--
Kun YIN,
Department of Geoengineering and Geoinformatics,
School of Earth Sciences and Engineering,
Nanjing University,
Hankou Road 22,
Geological Lab Building, Office 502,
Nanjing, 210093, P.R. China

Email : kyin.cn at gmail.com