Effects of basis set choice upon the atomization energy of the second-row compounds SO2, CCl, and ClO2 for B3LYP and B3PW91

The atomization energies of the species SO2, ClO2, and CCl have been calculated using the hybrid density functional approaches B3LYP and B3PW91. These functionals have been used in combination with the correlation-consistent basis sets cc-pVxZ and aug-cc-pVxZ (where x = D(2), T(3), Q(4), or 5). The impact of the newly revised correlation-consistent basis sets for second-row atoms (cc-pV(x+d)Z, aug-cc-pV(x+d)Z) upon the description of these systems has been assessed. Smooth convergence toward the Kohn-Sham limit is observed. The impact of the tight d function is particularly significant in the description of atomization energies for ClO2 and SO2 at the double-zeta and triple-zeta levels of basis sets, improving the energies by 13-17 and 9-10 kcal/mol, respectively.