This card is used to specify the type of spin-dependent calculation for spin along the (x, y, z) direction, along the z-axis by default. The SPIN card is required for the calculation of all spin-dependent effects, including XMCD and SPXAS .

Whenever spin-dependent calculations are made, the spin amplitude and
relative spin orientation should be specified in the `spinph` argument
of the POTENTIALS card.

If FEFF has been compiled with the parameter `nspx`=1 (default),
the values of the index `ispin` correspond to the following calculations:

The default `ispin`=0 is used for spin-independent calculations.

If FEFF is compiled with `nspx`=2, one simply uses `ispin`=1
or `ispin`=2 as needed, and the up and down spins are taken care of
automatically.
The spin-dependent potentials are calculated from the spin-dependent
densities, using von Barth-Hedin results for the uniform electron gas.
We use this approximation to construct the spin-dependent muffin-tin potential.
This should be fine for EXAFS, where small details of the potential are irrelevant,
but may not be good enough in the XANES region, where the self-consistent
spin-dependent muffin-tin potential can lead to better results.

* Make spin-up XMCD calculation (XMCD card must also be included) SPIN 1 XMCD

POTENTIALS card for spin-dependent calculations:

* GdFeO, spin-dependent * Note that SPIN card must also be present in feff.inp, as well as * additional cards specific to desired calculations POTENTIALS * ipot z tag lmax1 lmax2 xnatph spinph 0 64 Gd 3 3 0.1 7.0 (c sublattice) up 1 26 Fe 2 3 2 4.0 (a sublattice) up 2 26 Fe 2 3 3 -4.0 (d sublattice) down 3 8 O 2 3 12.0 0.0 (h sublattice) 4 64 Gd 3 3 2.9 7.0 (c sublattice) up