The augmented correlation consistent basis sets, when combined with coupled cluster or multireference configuration interaction methods, have been found to provide an accurate description of atomic electron affinities. The calculated EAs of boron and fluorine are summarized in Table 26 and the basis set convergence errors are plotted in Figure 13. The values of the EAs of these two atoms, 6.39 0.23 kcal mol (B) and 78.82 kcal mol" (F), respectively (corrected for spin-orbit effects), bracket the EAs of the other first-row atoms. [Pg.110]

The first point to note about the correlation-consistent basis sets in Table 8.16 is that the convergence is in all cases uniform and systematic - for the energies, for the bond distances, and for the bond angle. Scrutiny of the table reveals that, with each increment in the cardinal number, all errors are reduced by a factor of at least 3 or 4. Clearly, the correlation-consistent basis sets provide a convenient framework for the quantitative study of molecular systems at the Hartree-Fock level. We also note that the results for the cc-pVXZ and cc-pCVXZ basis sets are very similar. Apparently, the molecular core orbitals are quite atom-like and unpolarized by chemical bonding. In Hartree-Fock calculations, therefore, the use of the smaller valence cc-pVXZ sets is recommended. [Pg.317]

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