New relativistic effective core potentials for heavy elements Original Research Article

A relativistic ECP based on the AIMP method and with explicit relativistic no-pair operators included in the Hamiltonian is described. Calculated excitation energies of the third row transition metals and spectroscopic constants for the third row transition metal hydrides are presented. The results are compared with relativistic all-electron no-pair results. The agreement between the all-electron and the ECP results is very good.