[QE-users] Trouble with MoSe2

[AMOGH A .]

Hello folks!

I am having 3 problems with MoSe2.

   1. I got the correct electronic band structure of the MoSe2 unitcell,
   but when I try it for the supercell (3x3 or 5x5), or some doped version,
   the band plots look very "busy" and messed up (plots attached). The direct
   bandgap at the K-point also disappears. Nothing except *nat* and
   *atomic_positions* changed in the input files. Is this typical of
   large atomic systems? Is there a way to reduce the "business"? I read about
   "unfolding" the Brillouin zone but not too sure how it might help.
   2. I am trying to get the phonon dispersion and PhDOS for the monolayer.
   I am working with the un-relaxed unitcell having 3 atoms. I have been
   getting frequencies from -3000 cm^-1 to 2000 cm^-1 (plots attached). Can
   someone please tell me why I am getting such large negative frequencies and
   how to get the correct plot? I tried changing almost all parameters in the
   input file to no avail.
   3. MoSe2.dyn(i) files for some values of i, will have a string of
   asterisks in place of a few numbers which gives me a Fortran compiler error
   when I run q2r.x (QE version 7.4.1). Thus far, I have been going to the
   files, finding the asterisks where numbers *should* be, and replacing
   them with 0.000. Any idea why that happens (and how to fix it)?

Thanks for your help in advance!
Amogh A
Undergrad student at BITS Pilani, Hyderabad.

(GitHub and Google Drive links)
Github rep containing all the input files.
<https://github.com/AmoghA4/Quantum-ESPRESSO>
Unitcell band structure
<https://drive.google.com/file/d/1C_7zDhHir8eiHbNe2YyJhbrPSw7mSYjs/view?usp=sharing>
 v.s. supercell band structure
<https://drive.google.com/file/d/1Dfxv2r9vj9FsLcI3cq3QVpkys2_ePyii/view?usp=sharing>
 and oxygen-doped
<https://drive.google.com/file/d/1XtAbmdGoNS8EklQ6GuJADlz6fLZREHmP/view?usp=sharing>
.
Phonon dispersion plot I got
<https://drive.google.com/file/d/1plCzIl364o0ZEIkLxQujZ3Sg7hZpRHwU/view?usp=sharing>
 v.s. the correct one
<https://www.researchgate.net/figure/The-phonon-dispersion-of-monolayer-a-MoS2-b-MoSe2-b-and-c-MoTe2-Non-negative_fig3_377939317>
.

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