The magnetic and magneto-optical properties of NdX (X = P, As, Sb, Ri) in t
he ferromagnetic phase derived from an electronic structure calculation hav
e been presented. The calculation is performed using the local spin-density
approximation (LSDA) and also the LSDA corrected with the Coulomb interact
ion LI (the LSDA + U). The LSDA + U density of states at the Fermi level is
small and the carrier density is also low. The magnetism in NdP, NdAs and
NdSb is found to be dominated by a large orbital contribution coupled antip
arallel to the spin moment. The anisotropic mixing between the p states of
X and the f states of Nd provides the large off-diagonal optical conductivi
ty.