MODIFIED AR CORE ABINITIO RELATIVISTIC EFFECTIVE POTENTIALS FOR TRANSITION-METALS SC THROUGH CU

Ab initio relativistic effective potentials (REP) for first row transition metals show large errors in excitation energies between s2d(n), s1d(n+1), and d(n+2) states if only 4s and 3d electrons are included in the valence space (Ar core). These errors are diminished when the potentials are generated including also 3s and 3p electrons in the valence space (Ne core), but thus one of the main advantages of the REP procedure is lost. The origin of such errors in Ar core potentials is first analyzed in this work and a modification to their construction is proposed which, while retaining the Ar core choice, clearly improves the general performance of the potentials.