Small-core multiconfiguration-Dirac-Hartree-Fock-adjusted pseudopotentials for post-d main group elements:: Application to PbH and PbO

Relativistic pseudopotentials (PPs) of the energy-consistent variety have been generated for the post-d group 13-15 elements, by adjustment to multiconfiguration Dirac-Hartree-Fock data based on the Dirac-Coulomb-Breit Hamiltonian. The outer-core (n-1)spd shells are explicitly treated together with the nsp valence shell, with these PPs, and the implications of the small-core choice are discussed by comparison to a corresponding large-core PP, in the case of Pb. Results from valence ab initio one- and two-component calculations using both PPs are presented for the fine-structure splitting of the ns(2)np(2) ground-state configuration of the Pb atom, and for spectroscopic constants of PbH (X (2)Pi(1/2), (2)Pi(3/2)) and PbO (X (1)Sigma(+)). In addition, a combination of small-core and large-core PPs has been explored in spin-free-state shifted calculations for the above molecules. (C) 2000 American Institute of Physics. [S0021-9606(00)30531-1].