[Wien] Orientation of Atomic Spin Moments

[Chiung-Yuan Lin]

Dear Dr Laskowski,
  Thanks a lot for the detailed instructions. They really helps.

I still have questions on your following comments.

> S_z is a z projection of total spin moment, in collinear calculations only
> this quantity is accessible. The direction of z matters only when SOC is
> present, otherwise spins of your system can be freely rotated.

In a collinear non-SOC calculation, if the atomic spin can be freely
rotated, shouldn't the S_z change? Or is the z-axis always rotated
with the spin? How is the spin z-axis related to the global and local
coordinates that are defined in Wien2k (in case.struct)? I may be
asking very basic questions. It would be nice that you can give some
references that discuss these basics in detail.

Thanks,
Chiung-Yuan