Spin-dependent pseudopotentials

Near degeneracies and strong spin polarization are characteristics of transition metals that offer challenges to the pseudopotential approximation. Here we investigate the spin dependence of pseudopotentials generated from atomic, all-electron density-functional calculations. Different spins are found to require different pseudopotentials for any spin-polarized atom. Ignoring this leads to significant errors in the representation of all but the nonmagnetic configurations. Including a correction that is linear in the local spin polarization results in a spin-dependent expression, which dramatically improves the transferability of the atomic pseudopotential beyond previous nonlinear core corrections.