A comparison of correlation-consistent and Pople-type basis sets

Correlation-consistent basis sets are compared with Pople-type basis sets 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 triple zeta plus tight d basis sets. However, after inclusion of a higher-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 step yields the best results. The G2(B3LYP/MP2/CC) approach works bettern than a PCIX approach at the spin-unrestricted CCSD(T) level.