[Wien] Re: The structure factors

[Marek Necas]

Dear Professor Blaha,

thank you very much for your explanation of the output3 file.
You are of course right with bohr/angstrom conversion. I should
know that the lattice constants in the output3 file are in bohr
units.

Most probably the values from the paper will be really the atomic
scattering (form) factors, as they progressively decrease with 
increasing sin O/L in similar manner as in International Tables 
for Crystallography. There is one exception (222 reflection), 
what is probably because of the strong non-spherical density 
contribution.

Your comments are very good starting point for my next experiments.

Sincerely,

Marek Necas


> 
> The density within the APW methods comes from atomic spheres (centered
> at the nuclear positions) and the region between these spheres (called
> interstital or in case.output3 "structure factors from out").
> 
> The many colums for the contributions within the sphere are due to the
> expansion of the density into spherical harmonics (lattice harmonics) and
> each one gives a contribution to the structure factor (of course the L=0 M=0
> contribution dominates by far).
> 
> Your lattice constant problem is simply bohr-Angstrom conversion ?
> WIEN2k does everything in atomic units, i.e. in bohr  (0.529177 bohr=1 Ang)
> When you specify 5.4 ANG in w2web (do NOT forget to choose ANG !!!)
> it will be automatically converted into bohr.
> 
> Thus it is "X - RAY STRUCTURFACTORS" which are of interest for your.
> 
> Finally, the problem of "comparison" is most likely that for an elemental
> solid one can either calculate the structure factor (of the unit cell, this
> is what is given in case.output3), 
> or alternatively give the "atomic form factor"
> (remember the structure factor is composed as sum of atomic formfactors times
> a phasefactor (exp(i K r); where r are the positions of the atoms in the
> unit cell.
> 
>