Accurate atomic Gaussian basis functions for first-row atoms .1. Contracted basis sets derived from 9s5p primitives

Contracted Gaussian basis sets (9s5p/5s3p), (9s5p/5s2p), (9s5p/4s2p), (9s5p/3s2p) and (10s5p/4s2p), (10s5p/3s2p) are presented for the ground states of the first-two atoms of the periodic table. The primitive basis (10s5p) is derived from a (9s5p) Gaussian basis by doubling one s-type function. A two-step procedure is applied for the construction of all basis sets reported. The atomic total energy is first optimized in the SCF approximation with respect to atomic exponential parameters and then with respect to the contraction coefficients. The energy functional is determined with a maximal error of less than 1.0 x 10(-8) E(h) in both cases. The basis sets are further tested by performing geometry optimizations of the LiH, BeH2, BH3, CH4, NH3, OH2 and FH molecules at the Hartree-Fock level.