The real and imaginary components of Bloch function can be converted into the magnitude and phase terms accordingly. When the Bloch function is visualized in VNL via isosurface plot, one can choose the magnitude or phase to show the it.
From the charge density [tex]\rho[/tex] in a spin-polarized calculation, one can easily get the spin density ([tex]\Delta \rho =\rho_{up}-\rho_{dn}[/tex]), where [tex]\rho_{up}[/tex] and [tex]\rho_{dn}[/tex] are the spin-up and spin-down charge densities, respectively. And then visualize the spin density via contour plot or volume plot. This plot of spin density may be more clear to show the distribution of spin.