Compatibility of correlation-consistent basis sets with a hybrid Hartree-Fock/density functional method

The present study examines the feasibility of combining the correlation-consistent basis sets developed by Dunning and coworkers with the hybrid Hartree]Fockrdensity functional method B3LYP. Furthermore, Ž . extrapolation to the complete basis set CBS limit minimizes errors due to the presence of an incomplete basis set and can act as a rigorous test of the limitations of the B3LYP method. Equilibrium geometries, energies, and harmonic vibrational frequencies were determined for a series of well-studied, yet computationally challenging, small inorganics and their respective ions. The results were then extrapolated to the CBS limit, where applicable, and compared to experiment. It was found that a union between the hybrid Hartree]Fockr density functional B3LYP method and Dunning’s augmented correlationconsistent basis sets gave results that were comparable to molecular orbital methods that explicitly account for electron correlation. Furthermore, the minimum basis set necessary to attain reasonable results for the systems studied was aug-cc-pVTZ. Upgrading to the aug-cc-pVQZ level and subsequent Correspondence to: R. A. Wheeler; e-mail: rawheeler@ ou.edu Contractrgrant sponsors: University of Oklahoma; NSFr National Center for Supercomputing Applications; NSFrCornell Theory Center; Advanced Research Projects Agency; IBM Corp.; NIH; Silicon Graphics Contractrgrant sponsor: Oklahoma Center for the Advancement of Science and Technology; contractrgrant number: H97091 ( ) Journal of Computational Chemistry, Vol. 20, No. 2, 207]216 1999 Q 1999 John Wiley & Sons, Inc. CCC 0192-8651 / 99 / 020207-10