First principles study of magnetism of NpTAl ( T = Co , Ni , Rh ) compounds

First-principles calculations based on density-functional theory were performed for NpTAl ( T = Co , Ni , Rh ) compounds for the first time. The electronic density of states, bonding properties and equilibrium volume were studied using relativistic full-potential APW plus local orbitals calculations. The magnetocrystalline anisotropy energy was estimated from total-energy calculations and the c -axis and a -axis were predicted to be the easy axis of magnetization in the cases of NpRhAl, NpCoAl, and NpNiAl, respectively. Finally, we employed the LSDA + U method to mimic orbital polarization and to obtain the correct total magnetic moments in experimental equilibrium for NpNiAl and NpRhAl and to predict the value of the moment for NpCoAl.