ACCURATE UNIVERSAL GAUSSIAN-BASIS SET FOR HELIUM THROUGH CALCIUM GENERATED WITH THE GENERATOR-COORDINATE DIRAC-FOCK METHOD

The recently developed generator coordinate Dirac-Fock method for clos ed-shell atoms is applied to generate an accurate universal gaussian b asis set for the atoms from He (Z = 2) through Ca (Z = 20). The Dirac- Fock-Coulomb and Dirac-Fock-Breit energy results obtained with our uni versal gaussian basis set are compared with previous universal gaussia n basis set Dirac-Fock-Coulomb and Dirac-Fock-Breit results, and with corresponding results obtained by numerical-finite-difference calculat ions. In general, our Dirac-Fock-Coulomb energies are better than the corresponding Dirac-Fock-Coulomb energies attained with the previous u niversal gaussian basis set, and are in excellent agreement with those obtained by the numerical-finite-difference method. For He and Be ato ms, the Dirac-Fock-Coulomb energies obtained with our universal gaussi an basis set are lower than the corresponding Dirac-Fock-Coulomb energ ies obtained by both numerical-finite-difference calculations and a pr evious universal gaussian basis set. (C) 1997 Elsevier Science B.V.