MODIFIED RELATIVISTIC EFFECTIVE POTENTIALS FOR TRANSITION-ELEMENTS

Ab initio effective core potentials for first row transition metals are known to show large errors in excitation energies between s2d(n), s1d(n+1), and d(n+2) states if an [Ar] core is selected to set the valence space. After analyzing the origin of such errors in [Ar] core potentials, a modification to their construction is proposed that, while retaining this core choice, considerably improves the general performance of the potentials.