Correlation consistent basis sets for molecular core-valence effects with explicitly correlated wave functions: The atoms B–Ne and Al–Ar

摘要

Correlation consistent basis sets have been optimized for accurately describing core-core andcore-valence correlation effects with explicitly correlated F12 methods. The new sets, denotedcc-pCVnZ-F12 (n=D, T, Q) and aug-cc-pCF12VnZ (n=D, T, Q, 5), were developed by augmentingthe cc-pVnZ-F12 and aug-cc-pVnZ families of basis sets with additional functions whose exponentswere optimized based on the difference between all-electron and valence-electron correlationenergies. The number of augmented functions added is fewer, in general, than in the standardcc-pCVnZ and cc-pwCVnZ families of basis sets. Optimal values of the geminal Slater exponent foruse with these basis sets in MP2-F12 calculations are presented and are also recommended forCCSD-F12b calculations. Auxiliary basis sets for use in the resolution of the identity approximationin explicitly correlated calculations have also been optimized and matched to the newcc-pCVnZ-F12 series of orbital basis sets. The cc-pCVnZ-F12 basis sets, along with the newauxiliary sets, were benchmarked in CCSD(T) F12b calculations of spectroscopic properties on aseries of homo- and heteronuclear first and second row diatomic molecules. Comparing the effectsof correlating the outer core electrons in these molecules with those from conventional CCSD(T) atthe complete basis set limit, which involved calculations with new cc-pCV6Z basis sets for thesecond row elements that were also developed in the course of this work, it is observed that the F12values are reasonably well converged already at just the triple-ξ level.