All basis sets, ranging in size from minimal STO-nG to polarized double-valence n-31G*, correctly predict that NH3 has a higher proton affinity than OH2 and SH2 but most reverse the known order of the latter two. 4–31G* results are in good agreement with experiment with regard to absolute as well as relative proton affinities of all three molecules. Further enlargement of the basis set and inclusion of electron correlation leads to no significant improvement of the 4-3 1G* results.
- Basis Set,
- Protonation Reactions,
Available at: http://works.bepress.com/steve_scheiner/268/