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 <[email protected]> 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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