[Wien] Wannier

[pluto]

Dear All,

I am interested to project WIEN2k band structure onto atomic orbitals, 
but getting complex amplitudes. For example, for graphene Dirac band 
(formed primarily by C 2pz) I would get two k-dependent complex numbers 
A_C2pz(k) and B_C2pz(k), where A and B are the two inequivalent sites, 
and these coefficients for other orbitals (near the Dirac points) would 
be nearly zero. Of course, for graphene I can write a TB model and get 
these numbers, but already for WSe2 monolayer TB model has several bands 
(TB models for WSe2 are published but implementing would be 
time-consuming), and for a generic material there is often no simple TB 
model.

Some time ago I looked at the WIEN2k wave functions, but because of the 
way LAPW works, it is not a trivial task to project these onto atomic 
orbitals. This is due to the radial wave functions, each one receiving 
its own coefficient.

I was wondering if I can somehow get such projection automatically using 
Wien2Wannier, and later with some Wannier program. I thought it is good 
to ask before I invest any time into this.

And I would need it with spin, because I am interested with systems 
where SOC plays a role.

The reason I ask:
Simple model of photoemission can be made by assuming coherent addition 
of atomic-like photoionization, with additional k-dependent initial band 
amplitudes/phases. One can assume that radial integrals in photoemission 
matrix elements don't have special structure and maybe just take atomic 
cross sections of Yeh-Lindau. But one still needs these complex 
coefficients to allow for interference of the emission from different 
sites within the unit cell. I think for a relatively simple material 
such as WSe2 monolayer, the qualitative result of this might be 
reasonable. I am not aiming at anything quantitative since we have 
one-step-model codes for quantitative.

Any suggestion on how to do this projection (even approximately) within 
the realm of WIEN2k would be welcome.

Best,
Lukasz


PD Dr. Lukasz Plucinski
Group Leader, FZJ PGI-6
Phone: +49 2461 61 6684
https://electronic-structure.fz-juelich.de/