A universal basis set for high-precision molecular electronic structure studies: correlation effects in the ground states of , CO, BF and

Abstract

High-precision many-body perturbation theory calculations are reported for a series of 14-electron diatomic systems in their ground electronic states at their respective equilibrium geometries using a universal basis set of even-tempered Gaussian primitive functions. Using a systematic approach previously developed for the molecule, calculations have been carried out for the CO and BF molecules and for the ion using the matrix Hartree-Fock approximation supplemented by a second-order many-body perturbation theory description of correlation effects. The basis set is distributed across the nuclear centres and the bond centre. Functions of s, p, d, f, g and h symmetry are included on each centre. Extrapolation procedures are employed to estimate the contribution of higher symmetry types to the electron correlation energy. The calculated and extrapolated correlation energies obtained are compared with the corresponding results obtained with some of the larger correlation consistent basis sets, with calculations employing explicitly correlated functions, and with empirical estimates of the correlation energy.