[Wien] bandstructure on slabs

[Lukasz Plucinski]

> I think you can remove surface state in the data file after you fingure out
> which one is surface state. I usually use atomic LDOS to locate the surface states'
> location in the band structure and removed it from original data file.
>
> Good luck.
>
> Xiliang Nie

Hello,

I make slab band structure calculations. WIEN is very good program to do
it, since it can calculate automatically k- and eigenvalue-resolved charge
inside the spheres. This gives you automatically surface states - its
implemented in w2web, and one can even make plots immediately and
automatically (called character plots).

I don't think it would be easy to separate H related states from the rest
of states. This is because none of the states are localized just on one
atom - surface states are the ones that have significantly more charge on
surface atoms (or/and first, second layer). But they still have some
amount of charge 'inside' the slab.

What you could do (and what is typically done) is to find out the surface
states one the interesting side of the slab (i.e. the side without H
atoms). Just make some arbitral criteria and seprate the surface states
from the rest of states. I don't know how much you know - technically at
first step you should play with the parameters in case.insp file
(mainly in line  # jatom, jtype, size of heavier ...) - then plot the band
structure. Later you probably need to write some script that takes the
eigenvalues and partial densities from one of the output files (it was
discussed in this list before which files to use).

In principle you could also just plot the whole thing including H atoms,
however, this is not the most elegant. But its ok I believe if you only
mention it.

I personally do not use H atoms to terminate slab - just use larger slab
with reconstructed surface on both sides. Its quite longer calculation but
as you see some problems are avoided. Its also difficult to say what
actually H atoms do to the slab. I also have a feeling that the larger the
slab is the easier for WIEN (or any other DFT code) to separate surface
and bulk states. This is because larger slab means more eigenvalues, means
more choice.

Again I don't know how much you know but there are
two more important things: do you know that its better to find theoretical
lattice constant for the bulk material and use it in slab claculation
(optimize in WIEN) ? Do you know you should relax the surface
theoretically before making slab band structure calculation (mini.
positions in WIEN) ?

You don't have to do these 2 things, however, if you don't do it you
should have a good answer why.

Best regards,

Lukasz