[DFTB-Plus-User] px, py, pz PDOS for graphene

[Peter Klaver]

Hi Bálint,

Thanks for the reply. After sending my question to the user list, someone suggested looking at the source code to see what is what. And indeed in the source file

dftbplus-24.1/src/dftbp/type/orbitals.F90

it says:

!> Names of the atomic orbitals in tesseral basis
  !> general set for f orbitals (not cubic), see
  !> http://winter.group.shef.ac.uk/orbitron/AOs/4f/equations.html
  character(lenOrbitalNames), parameter :: orbitalNames(-3:3,0:3) = reshape([&
      & '         ','         ','         ','         ','         ','         ','         ',&
      & '         ','         ','y        ','z        ','x        ','         ','         ',&
      & '         ','xy       ','yz       ','z2       ','xz       ','x2-y2    ','         ',&
      & 'y(3x2-y2)','x2+y2+z2 ','yz2      ','z3       ','xz2      ','z(x2-y2) ','x(x2-3y2)'&
      &], [7,4])

Having the order Py, Pz, Px was rather counter-intuitive to me, but I understand what it is now. :)

Kind regards,
Peter



> On 15 Oct 2025, at 18:16, Bálint Aradi <aradi at uni-bremen.de> wrote:
> 
> Dear Peter,
> 
> we use real tesserals, instead of complex spherical harmonics. For p orbitals, the m indexing is the following:
> 
> -1: py
> 0: pz
> 1: px
> 
> I hope, this helps.
> 
> Best regards,
> 
> Bálint
> 
> 
> On 10/8/25 1:19 PM, Peter Klaver wrote:
>> Hello people,
>> I am a bit unclear about the PDOS files produced in a calculation of graphene. I set
>> ShellResolved = Yes
>> OrbitalResolved = Yes
>> so for p PDOS on C atoms I get output files with two numerical indices, the second with values -1, 0, 1. I assumed the second index to be l_m
>> However, the DOS values in the files with indices -1 and 1 are nearly the  same, so when I subtract them or add them up to get values for px and py, the values are either twice as big as those reported by others, or the values are all very close to 0. However, the values in the files with indices -1 and 1 appear to already be equal to px and py PDOS?
>> Others reported PDOS for graphene e.g. at
>> https://docs.nanoacademic.com/rescu/getting_started/dos/pdos/
>> When I subtract and add the values in files with indices -1 and 1 the result is as in the first figure below, when I presume files with indices -1, 0, 1 to be px, pz, py, the outcome roughly matches the outcome in the url above, see second figure below. In both figures   below the Dirac cone at the Fermi level is not a sharp tip, due to the broadening I applied.
>> So do the files with indices -1, 0, 1 contain PDOS data for px, pz, py or for increasing values of l_m? Or is it something else still that I am missing?
>> Kind regards,
>> Peter Klaver
>> Screenshot 2025-10-08 at 12.00.22.png
>> Screenshot 2025-10-08 at 12.20.10.png
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> 
> 
> -- 
> Dr. Bálint Aradi
> Bremen Center for Computational Materials Science, University of Bremen
> http://www.uni-bremen.de/en/lmcqm/b-aradi
> 
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