[Pw_forum] reference energy of eigenvalue of Kohn-Sham equation

[yukihiro_okuno at fujifilm.co.jp]

Dear PWSCF users.

I want to calculate the band off set of semiconductor's hetero junction.
(semiconductor A/B junction)
In order to calculate the band offset value of valence band at the
interface,
I knew  the average potential of electrostatic potential, must be
calculated
in the super cell calculation of A/B hetero junction.
(Baldereschi, et al  Phys. Rev. Lett vol61 734 ) and the eigenvalue of
valence band top of semiconductors A and B, independently.
The band offset is defined by

Band offset of valence band = (Ea-Eb)+(delta V),

where Ea and Eb is the eigenvalue of the valence band top of the K.S.eq and
deltaV is
the difference of the average of the electrostatic potential of bulk like
region of
A and B semiconductor in the supercell.

By the way, why the  reference energy of the eigenvalue of the Kohn-Sham
equation
is the average of electro static potential ?  Where in the formalism, the
K.S eq  refers
the average of the electro static potential ?


Sincerely,

Yukihiro Okuno.