All-electron and pseudopotential study of the spin-polarization of the V(001) surface: LDA versus GGA - art. no. 172406

The spin-polarization at the V(001) surface has been studied by using diffe rent local [local spin-density approximation (LSDA)] and semilocal [general ized gradient approximation (GGA]) approximations to the exchange-correlati on potential of DFT within two ab initio methods: the all-electron tight-bi nding linear muffin-tin orbital atomic-sphere approximation and the pseudop otential linear combination of atomic orbitals code SIESTA (Spanish initiat ive for electronic simulations with thousands of atoms). A comparative anal ysis is performed first for the bulk and then for a N-layer V(001) film (7 less than or equal to N less than or equal to 15). The LSDA approximation l eads to a nonmagnetic V(001) surface with both theoretical models in agreem ent (disagreement) with magnetooptical Kerr (electron-capture spectroscopy) experiments. The GGA within the pseudopotential method needs thicker slabs than the LSDA to yield zero moment at the central layer, giving a high sur face magnetization (1.70 Bohr magnetons), in contrast with the nonmagnetic solution obtained by means of the all-electron code.