## Optimal Composition of Atomic Orbital Basis Sets for Recovering Static Correlation Energies

journal contribution

posted on 17.12.2015, 01:08 by Andrew
J. Wallace, Deborah L. CrittendenStatic correlation energies (

*E*_{stat}) are calculated in a range of basis sets for a chemically diverse collection of atoms and molecules. The reliability of a basis set in capturing*E*_{stat}is assessed according to the following: mean and maximum absolute deviations from near-exact*E*_{stat}estimates, monotonic convergence to the complete basis set limit, and ability to capture*E*_{stat}accurately independent of changes in geometry, molecular size, and electronic configuration. Within the polarization and correlation-consistent basis set series, triple-ζ basis sets are the smallest that can reliably capture*E*_{stat}. The cc-pVTZ basis set performs particularly well, recovering*E*_{stat}to chemical accuracy for all atoms and molecules in our data set. A series of customized basis sets are constructed by stripping polarization functions from, and swapping polarization functions among, existing basis sets. Basis sets without polarization functions are incapable of accurately recovering*E*_{stat}. Basis sets with a near-complete set of*s, p*, and*d*functions can approach chemical accuracy in maximum absolute error. However, this may be achieved at lower computational cost by using a well balanced triple-ζ basis set including*f*functions, along with a smaller number of*s, p*, and*d*functions. Recommended basis sets for calculating*E*_{stat}with increasing accuracy at increasing computational cost are 6-311G(2d,2p), cc-pVTZ, and cc-pVQZ stripped of*g*functions.