From Spinach Documentation Wiki
Finds the optimal magnetic susceptibility tensor that a user-supplied paramagnetic centre probability density must have in order to fit the PCS data supplied.
source_cube - paramagnetic centre probability density cube ranges - a six-element vector giving the extents of the probability density cube in Angstroms as [xmin xmax ymin ymax zmin zmax] nxyz - nuclear coordinates as [x y z] with multiple rows, at which PCS is measured, in Angstroms. expt_pcs - pseudocontact shift in ppm at each nucleus.
chi - optimised magnetic susceptibility tensor in cubic Angstroms. pred_pcs - predicted pseudocontact shift at each nucleus with the optimised mxyz and chi, ppm.
See the pseudocontact shift analysis tutorial for a detailed walkthrough.