Create a spin system object for pulse sequence simulation.
spin_sys(spin_params, ft, ref, precomp_jc_H = NULL, precomp_Iz = NULL)
spin system object.
an object describing the spin system properties.
transmitter frequency in Hz.
reference value for ppm scale.
use a precomputed J-coupling H matrix to save time.
use precomputed Iz matrices to save time.