[QE-users] highest peaks in DOS

[dlduran at uco.es]

Dear QE users,

  I have obtained the HOMO and LUMO levels of a perovskite. It is an
organic perovskite made up of slabs of I-Pb and an organic molecule
wit C, S, O and N. The HOMO is on the I atoms and the LUMO in the
S atoms, aproximately. The DOS show the last levels of the valence band
in the I and the first levels of the conduction band in the molecule,
which agrees with the previous results of the HOMO and LUMO levels.

  However, the atoms with the highest intensities of I and S in the DOS are not
those in which the HOMO and LUMO levels are. I expected to be the
same, it is, the brightest atoms of I to be the same of the
HOMO level and the DOS, and the brightest atoms of S to be the
same of the LUMO level and the DOS, but it not so.

  I don't know how to explain this effect. Any suggestion?

  I have made the following calculations (input_dft=vdw-df-cx always):

1. A geometric optimization. This initial prediction of both unit-cell
and atomic structure implements relaxations defined by calculations of both
forces and stresses and was completed at a 2175 eV (160 Ry) kinetic-energy
cutoff (and 640 Ry for the charge-density representation).

2. A self-consistent (scf, 4x4x4) calculation followed by a
non-self-consistent (nscf, 8x8x8) calculation, achieving convergence with
a kinetic-energy cutoff of 680 eV (50 Ry).

3. The extraction of the DOS, BS and electronic levels (HOMO, LUMO, ...)
using the QE post-processing tools.

  Thank you very much for your help and Happy Christmas, David.


--------------------------
David López Durán
Lecturer/Associate Professor (non-tenure track)
Department of Physics
University of Córdoba, Spain
Phone: +34 957 21 20 32
https://www.uco.es/organiza/departamentos/fisica/es/personal/personal-docente-e-investigador/149-david-lopez-duran
https://es.linkedin.com/in/davidlopezduran