[Wien] Spin texture in reciprocal space

[Paul Fons]

Dear All,
	I am trying to reproduce the results of some spin texture calculations on topological insulators in the literature, specifically the work of Basak et al in PRB84, 121401 (2011) on Bi2T3.  They calculated the spin texture (the helical nature) of the in-plane spin components in reciprocal space at the Fermi level (surface) using Wien2K.  I have reproduced the slab calculations and can see the surface bands so so-far so good. However, I am unsure how to go about calculating the expectation values for the spin in reciprocal space, e.g. what is called spin texture (I must admit I have some additional questions about quantization axes as well due to the lack of commutation among Sx, Sy, and Sz.  The plot of the spin texture in the paper showed for the 2D projected surface state, a "ring" of arrows following a locus of points described by a circle -- e.g. it demonstrated that the spin was helical.
  I did note the presence of a density matrix routine LAPWDM  in section 7.7 of the user guide which allows for the calculation of expectation values including spin, but only apparently in real space and only within the atomic spheres.  Any guidance as to how to go about calculating a spin texture map (e.g. the projected spin direction on the 2D fermi surface in reciprocal space of the above topologically insulating structure) would be greatly appreciated.  I have surveyed the literature, but there are no details of how the spin texture maps were calculated in any of the papers I have read.  Thanks for any help in advance.
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