Revised Basis Sets for the LANL Effective Core Potentials

We suggest a new contraction of the basis sets associated with the Hay-Wadt relativistic effective core potentials (RECPs) for the main group and transition metal atoms. These bases are more suitable for density functional theory investigations than the previous 'double-ζ' contractions based upon Hartree-Fock atomic results. The original Hay-Wadt primitives are now contracted [5s5p3d], [4s4p3d], and [4s4p3d] for the first, second, and third transition series, respectively, and denoted as LANL2TZ basis sets. For the main group atoms, we advocate using a completely uncontracted basis denoted LANL08. While modestly extending the size of the basis, the resulting sets should be suitable for both DFT and wave…