The performance of the Becke-Lee-Yang-Parr (B-LYP) density functional theory with various basis sets

The performance of a recently introduced hybrid of density functional theory and Hartree-Fock theory, the B-LYP/HF procedure, has been examined with a variety of basis sets. We have found that even the relatively small 6-31G* basis set yields atomization energies, ionization potentials and proton affinities whose mean absolute error, compared with a large body of accurate experimental data, is only 6.45 kcal/mol. We have also found that the addition of a “higher-level correction” (of the type used in G2 theory) to the B-LYP/HF total energies reduces the mean absolute error to 4.14 kcal/mol.