AB-INITIO CALCULATIONS CALCULOS DE PRIMEROS PRINCIPIOS ELECTRONIC PROPERTIES FERMIONES PESADOS HEAVY FERMIONS HIGHLY CORRELATED SYSTEMS PROPIEDADES ELECTRONICAS SISTEMAS FUERTEMENTE CORRELACIONADOS Calculations Cerium Cerium compounds Cerium oxides Co-doped Cobalt Electron gas First-principles calculation Magnetic moments Oxygen Oxygen vacancies Semiconductor doping article iron A. Ceria A. Diluted magnetic oxides Ab initio Ab initio calculations BOSONES BOSONS Barium compounds Bulk properties