[QE-users] Inaccurate bandstructure of InSb with PPs from QE PP-library

[Manu Hegde]

You never get an optical bandgap with DFT. I am not familiar with InSb.
Looks like GGA or LDA level theory might give metallic behavior as in InAs.
You may have to use hybrid-DFT or GGA+U. You may have to look into more in
literature.

On Wed, Oct 28, 2020 at 5:06 AM Ritwik Das <ritwik.das29 at gmail.com> wrote:

> *Why the inclusion of '4d' electrons in the pseudopotential of In and Sb
> giving erroneous InSb electronic bandstructure in Quantum Espresso?  *
>
> Dear all,
>
> I am struggling to obtain proper electronic band structure of InSb with
> pseudopotentials (PP) available on the QE PP-library.
>
>
> I was trying to obtain electronic bandstructure of InSb using Quantum
> Espresso (QE). At first, I used PBE pseudopotentials (with/without
> spin-orbit-coupling [SoC] and ultrasoft/PAW) available on the
> QuantumEspresso website. But in any case, I didn’t get an accurate band
> structure, there is no bandgap and also with SoC heavy-hole (HH) and light
> hole (LH) bands are separated on GAMMA high-symmetry points
> (InSb-PBE-PAW-SoC-conf1.png ). All those pseudopotentials (PP) of In and Sb
> available on the QE have taken all 10 electrons of 4d orbital as their
> valence electrons (for In: 4d10 5s2 5p1, for Sb: 4d10 5s2 5p3) along with
> 5s and 5p and rests as the core electrons.
>
> But when I generated PBE PPs by myself without taking 4d electrons as
> valence electrons (for In: 5s2 5p1, for Sb: 5s2 5p3), those PPs gave me
> quite an accurate bandstructure (PBE-PAW-SOC-conf2.png).
>
> My question is, why the inclusion of 4d electrons in the valence cell in
> the PP of In and Sb (which are the default and believed to be the most
> optimized configuration for PP) is not giving accurate bandstructure of
> InSb?
>
> Thank you in advance.
>
>
> Regards,
>
> Ritwik Das
> ---
> Ritwik Das
>
> C2N UMR CNRS 9001 - Université Paris-Saclay
>
> Department: Physics (Nanoelectronics)
>
>
>
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