Breakdown of the pseudopotential approximation for magnetic systems: Predicting magnetic quenching at the V„001... surface with spin-dependent pseudopotentials

Both experimentally @R.L. Fink et al., Phys. Rev. B 41, 10 175 ~1990!# and using all-electron densityfunctional theory ~DFT! methods, the V~001! surface exhibits little or no magnetization. Very recently, independent pseudopotential DFT calculations demonstrated the breakdown of the pseudopotential approximation, showing large magnetic moments at the surface of a V~001! slab. Here we demonstrate that use of spindependent pseudopotentials systematically corrects the inaccuracies of conventional spin-neutral pseudopotentials, producing results consistent with all-electron ones. We also show how the use of the spin-dependent pseudopotentials allows one to achieve a high level of accuracy without the numerical difficulties and cost associated with accurate spin-neutral pseudopotentials.