AB INITIO CALCULATIONS CALCULOS DE PRIMEROS PRINCIPIOS ELECTRONIC PROPERTIES Electronic structure HAMILTONIANO MODELO Lanthanum compounds MAGNETIC PROPERTIES MAGNETISMO NO COLINEAL MODEL HAMILTONIAN Magnetic moments NONCOLLINEAR MAGNETISM Noncollinear magnetism PROPIEDADES ELECTRONICAS PROPIEDADES MAGNETICAS Transition metals Ab initio calculations Anisotropic interactions Anisotropy Approximation theory Band structure Calculations Chains Crystal atomic structure Crystal impurities Crystallization Electronic transport properties Extended Heisenberg model Fermi liquid behavior Fermi liquids Fermions