[Pw_forum] Band Offsets too large

[Dae Kwang Jun]

Dear Mostafa Youssef,

I believe that I did that. I am not sure whether we both have the same
thing on mind, however. Here is what I did. I calculated the band
structures for both AlAs and GaAs using pw.x with calculation = 'bands'
after the scf calculations. The VB Maxima of AlAs and GaAs occur at the k
point gamma.  The bulk band structure calculations are done with 8
electrons for both GaAs and AlAs (I used the same pseudopotential that I
used for the interface calculation). Thus, I used the 4th energy at the
gamma k point in the AlAs.bands.dat file and the GaAs.bands.dat file. I
compared my band structures with literature, and I believe that they are
correct. From the interface calculation I find which compound has a higher
average electrostatic potential. I added the absolute value of
the difference in electrostatic potential from the interface
calculation  to the valence band energy of that compound (the one with
higher average electrostatic potential). I then substracted from this value
the energy of the valence maximum of the other compound. And I get the
(wrong) high value. Sorry for the long email. Please let me know your
thoughts.

Sincerely,

Dae Kwang Jun

On Thursday, 30 June 2016, Mostafa Youssef <myoussef at mit.edu> wrote:

> Dear Dae Kwang Jun,
>
> You also need 2 bulk calculations for AlAs and GaAs to get their band
> edges with respect to to their bulk electrostatic potentials. Then you can
> use the interface potential to align the band edges of the two
> semiconductors.  It looks like you missed this step.
>
>
>
> Mostafa
> MIT
>
>
> <http://www.mail-archive.com/search?l=pw_forum@pwscf.org&q=from:%22Dae+Kwang+Jun%22>
>
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