[QE-users] Integrated oribtal resolved DOS does not equal number of electrons

[Schön, Carl-Friedrich]

Dear QE Users,

I have a question regarding the integrated orbital-projected DOS:
I have used projwfc.x to calculate SnSe mp-2168. If I integrate the DOS I get from the k.pdos_tot file:

# E (eV)  dos(E)    pdos(E)
 -39.023  0.648E-02  0.648E-02
 -39.013  0.868E-02  0.868E-02
 -39.003  0.116E-01  0.116E-01
 -38.993  0.154E-01  0.154E-01
…

I get a value that is close enough to the number I expect, i.e. 59.997/60 . If I use the pdos however, I lose quite a margin: 59.86/60 , which is quite significant.
I am no expert (while I should be by now) in the theory behind these calculations, but am I suspecting correctly that the missing electrons are getting lost, as they would be projected to orbitals I do not include (lets say some f-orbitals that very slightly hybridize, but are not included in the orbitals I project unto)? Or is this „just“ a numeric issue during projection?

According to the archives, the spilling factor should give an indication of the difference, which is: 0.0021 for me, but I don’t understand how that number represents what I see in the integrated DOS. It seems to be also fairly small for my calculation.

Are there any „tricks“ to decrease this discrepancy?

Thank you and all the best,

Carl-Friedrich Schön, PhD Student, RWTH Aachen University
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