[Pw_forum] how to judge movement of HOMO and LUMO

[Sclauzero Gabriele]

Dear Rajdeep Banerjee,

    I think what is used as reference potential is the bare ionic potential + Hartree potential (V_bare + V_H). I kind of justification for that is given in this older paper by van de Walle & Martin (http://journals.aps.org/prb/pdf/10.1103/PhysRevB.35.8154) about band lineups at heterointerfaces.

I agree with Nicola that the problem is subtle, given that a pure bulk calculation for an infinite solid cannot provide absolute energy levels.
Hopefully someone with clearer ideas than me will be able to suggest alternative solutions.

Best,

GS


Dear Sclauzero  Gabriele,
                                    I looked at the paper you suggested (http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.101.046405) where it was said that the "common reference level (phi) " is calculated as the "cell average of the local potential originating from the ionic pseudopotentials" which I guess can be calculated from the pseudopotentials used. Can you suggest any functional form for this calculation of phi ? or indicate how to generate it from the pseudopotentials used?

As far as I understand, after defining phi, the CBM and VBM can be described by:


CBM = Ec - phi
VBM = Ev - phi

where Ec and Ev are LUMO and HOMO respectively.

Thank you very much for all the help.

Rajdeep Banerjee
JNCASR,
Bangalore, India

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Dr. Gabriele Sclauzero
Materials Theory - ETHZ
ETH Zurich, HIT G 43.2
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