Basis set and electron correlation effects on the electron affinities of first row atoms

The electron affinities of boron, carbon, oxygen, and fluorine atoms have been evaluated by Mo/ller–Plesset perturbation calculations through complete fourth order using several large basis sets. The convergence of the perturbation series has been evaluated carefully by means of modified coupled cluster methods. Large basis sets and electron correlation effects involving higher substitutions are found to be important in the accurate calculation of electron affinities. Triple substitutions are particularly important in the correlation treatment, contributing more than 0.2 eV to the electron affinities of O and F. The electron affinities of all the systems are calculated to be within 0.1 eV of the corresponding experimental values.