ON THE PERFORMANCE OF LARGE GAUSSIAN-BASIS SETS FOR THE COMPUTATION OF TOTAL ATOMIZATION ENERGIES

The total atomization energies of a number of molecules have been computed using an augmented coupled-cluster method and [5s4p3d2 f1g] and [4s3p2d1f] atomic natural orbital (ANO) basis sets, as well as the correlation consistent valence triple zeta plus polarization (cc-pVTZ) and correlation consistent valence quadrupole zeta plus polarization (cc-pVQZ) basis sets. The performance of ANO and correlation consistent basis sets is comparable throughout, although the latter can result in significant CPU time savings. Whereas the inclusion of g functions has significant effects on the computed SIGMAD(e) values, chemical accuracy is still not reached for molecules involving multiple bonds. A Gaussian-1 (G1) type correction lowers the error, but not much beyond the accuracy of the G1 model itself. Using separate corrections for sigma bonds, pi bonds, and valence pairs brings down the mean absolute error to less than 1 kcal/mol for the spdf basis sets, and about 0.5 kcal/mol for the spdfg basis sets. Some conclusions on the success of the Gaussian-1 and Gaussian-2 models are drawn.