Orbital partitioning errors in transition metal relativistic effective potentials

Abstract

The large errors in atomic excitation energies of the first transition elements (seen in SCF calculations using Ar-core relativistic effective potentials) can be rationalized in terms of the partitioning of the 4s orbital as required to form nodeless pseudoorbitals. We are able to show that with the partitioning revised to better represent the 4s electron density (and therefore critical coulombic interactions) in the region dominated by the 3s subshell, errors can be dramatically reduced. Such potentials would make large transition metal cluster calculations simpler and might be appropriate for quantum Monte Carlo work.