[QE-users] U correction, transferability

[Stefano de Gironcoli]

Dear Sergey,

        if you calculate the projected DOS you can see which atoms are 
involved in the states at the edges of the Valence and Conduction Bands. 
moreover you can see which angular momenta are participating into the 
frontier states...

       this should tell you what's going on. whether the states involved 
are not affected by the U part of the Hamiltonian or some more tricky 
cancellation is happening

      HTH

stefano


On 10/05/21 00:35, Sergey Lisenkov wrote:
> Dear users and developers,
> I have a question about transferability of U value computed with HP code.
> I have two materials, lets call them "A" and "B". "B" contains Mn 
> atoms, so I calculated U self-consistently using HP code (U 
> calculation - relax with U - U calculation - relax with U until U is 
> converged within 0.01 eV). Without "U" band gap of material "B" is 2.6 
> eV, with U - 4.7 eV. Material "A" does not have transition metal 
> atoms, so I used plain DFT for this. Bandgap for "A" is ~4.6 eV.
> Now I study "A"-"B" superlattices - layers of "A" material alternating 
> with layers of "B" material. What I found that band gap with and 
> without U correction I calculated before is almost the same - ~2.6 eV.
> Now I'm curious to know why there is no difference in band gap in 
> those two calculations. Is it possible that I have to calculate U 
> correction for this new material - "A/B" superlattice?
> Thanks,
>  Sergey
> Physics Department,
> USF
>
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