Molecular energies and properties from density functional theory: Exploring basis set dependence of Kohn - Sham equation using several density functionals

Ž The performance of four commonly used density functionals VWN, BLYP, BP91, and Becke’s original three-parameter approximation to the adiabatic connection formula, referred to herein as the adiabatic connection method or . w ACM was studied with a series of six Gaussian-type atomic basis sets DZP, Ž .x 6]31G**, DZVP, TZVP, TZ2P, and uncontracted aug-cc-pVTZ UCC . The geometries and dipole moments of over 100 first-row and second-row molecules and reaction energies of over 300 chemical reactions involving such molecules were computed using each of the four density functionals in combination with each of the six basis sets. The results were compared to experimentally determined values. Based on overall mean absolute theory versus experiment errors, it was found that ACM is the best choice for predictions of both energies w Ž . of reaction overall mean absolute theory versus experiment error MATvEE of Ž . x 4.7 kcalrmol with our most complete UCC basis set and molecular geometries Žoverall MATvEE of 0.92 pm for bond distances and 0.888 for bond angles with . Ž the UCC basis set . For routine calculations with moderate basis sets those of . double-z type: DZP, 6]31G**, and DZVP the DZVP basis set was, on average, the best choice. There were, however, examples of reactions where significantly Ž larger basis sets were required to achieve reasonable accuracy errors F 5 . kcalrmol . For dipole moments, ACM, BP91, and BLYP performed comparably Žoverall MATvEE of 0.071, 0.067, and 0.059 debye, respectively, with the UCC *Author to whom all correspondence should be addressed. E-mail: [email protected] Present address: Department of Chemistry, University of Arkansas, Fayetteville, AR 72701. ( ) Journal of Computational Chemistry, Vol. 18, No. 6, 775]795 1997 Q 1997 by John Wiley & Sons CCC 0192-8651 / 97 / 060775-21 SCHEINER, BAKER, AND ANDZELM . basis set . Basis sets that include additional polarization functions and diffuse functions were found to be important for accurate density functional theory predictions of dipole moments. Q 1997 by John Wiley & Sons, Inc.