GAUSSIAN-BASIS SETS FOR USE IN CORRELATED MOLECULAR CALCULATIONS .6. SEXTUPLE-ZETA CORRELATION CONSISTENT BASIS-SETS FOR BORON THROUGH NEON

The family of correlation consistent polarized valence basis sets (cc- pVXZ) has been extended to include sextuple zeta sets (cc-pV6Z) for th e atoms boron through neon. Potential energy functions have been calcu lated with these sets for the electronic ground states of N-2 and HF u sing a number of correlated wave functions: MP2, MP3, MP4, CCSD, CCSD( T) and CAS+1+2. Spectroscopic constants have been calculated for each level of theory and have been compared with experiment. Combining thes e results with those of prior studies, complete basis set limits have been estimated for E(e), D-e and r(e). It is found that the cc-pV6Z ba sis sets yield dissociation energies that are within 0.6-0.8 kcal mol( -1) (N-2) and 0.1 kcal mol(-1) (HF) of the estimated CBS limits. Addin g core-core and core-valence contributions to the CCSD(T) CBS limits y ields D-e's that are within 0.1 kcal mol(-1) of the experimental value s.