| Full text | |
| Author(s): |
Total Authors: 2
|
| Affiliation: | [1] Univ Estadual Campinas, Inst Quim, BR-13083970 Campinas, SP - Brazil
[2] Ctr Reg Univ Espirito Santo do Pinhal, BR-13990000 Espirito Santo Do Pinhal, SP - Brazil
Total Affiliations: 2
|
| Document type: | Journal article |
| Source: | International Journal of Quantum Chemistry; v. 119, n. 10 MAY 15 2019. |
| Web of Science Citations: | 0 |
| Abstract | |
Extrapolation formulas based on power and exponential formulas, as well as alternatives from a Taylor series, were tested and used with density functional theory (DFT) for the calculation of enthalpies of formation. The following four functionals were analyzed: B3LYP, BMK, M06-2X, and B2PLYP. Preliminary tests pointed to B2PLYP and B3LYP as the best and worst functionals, respectively. Taylor series expressions were as accurate as the power formulas and presented better performance than the exponential equation. The power formula (Equation (2)) and one of the simplest Taylor expressions (Equation (13)) were selected for the calculations with B3LYP and B2PLYP, with further empirical adjustments based on the higher level correction (HLC) and scaling of the experimental atomization energies used to calculate enthalpies of formation. HLC improved the B3LYP mean absolute error (MAE) from approximately 4.3 to 3.5 kcal mol(-1) using both extrapolation alternatives. For B2PLY, the MAEs were improved from 2.7 to 2.6 kcal mol(-1). Regarding the G3/05 test set, a significant improvement in the MAEs around 2.5 and 1.5 kcal mol(-1) were achieved using B3LYP and B2PLYP, respectively. The accuracy obtained from these empirical corrections was equivalent to other composite methods. The MAEs from B3LYP and B2PLYP may be suggested as ranges for the possible accuracy to be achieved by some DFT methods. The empirical corrections suggested in this work are improvements that may be considered to provide acceptable accuracy for enthalpies of formation and possibly other properties. (AU) | |
| FAPESP's process: | 13/08293-7 - CCES - Center for Computational Engineering and Sciences |
| Grantee: | Munir Salomao Skaf |
| Support Opportunities: | Research Grants - Research, Innovation and Dissemination Centers - RIDC |
| FAPESP's process: | 17/11485-6 - Computational and theoretical developments based on ab initio methods and the Density Functional Theory |
| Grantee: | Rogério Custodio |
| Support Opportunities: | Regular Research Grants |