A COMPARISON OF CORRELATION-CONSISTENT AND POPLE-TYPE BASIS-SETS

Correlation-consistent basis sets are compared with Pople-type basis s ets for the calculation of atomization energies using the G2(B3LYP/MP2 /CC) approach. Without a higher-level correction, the smallest errors are found for the augmented-correlation-consistent polarized valence t riple zeta plus tight d basis sets. However, after inclusion of a high er-level correction, the combination of the 6-311G* basis set for the high-level correlation treatment and 6-311+G(3df, 2p) for the MP2 ste p yields the best results. The G2(B3LYP/MP2/CC) approach works better than a PCIX approach at the spin-unrestricted CCSD(T) level.