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Basis set effects in the description of the Cl-O bond in ClO and XClO isomers (X=H,O,Cl) using DFT and CCSD(T) methods.pdf (2.46 MB)

Basis Set Effects in the Description of the Cl-O Bond in ClO and XClO Isomers (X=H,O,Cl) Using DFT and CCSD(T) Methods

preprint
submitted on 12.04.2018, 17:54 and posted on 13.04.2018, 14:34 by Oscar Ventura, Kenneth Irving, Martina Kieninger

The performance of a group of density functional methods of progressive complexity for the description of the ClO bond in a series of chlorine oxides was investigated. The simplest ClO radical species as well as the two isomeric structures XClO/ClOX for each X=H, Cl and O were studied using the PW91, TPSS, B3LYP, PBE0, M06, M06-2X, BMK and B2PLYP functionals. Geometry optimizations as well as reaction enthalpies and enthalpies of formation for each species were calculated using Pople basis sets and the (aug)-cc-pVnZ Dunning sets, with n=2-6. For the calculation of enthalpies of formation, atomization as well as isodesmic reactions were employed. Both the precision of the methods with respect to the increase of the basis sets, as well as their accuracy, were gauged by comparing the results with the more accurate CCSD(T) calculations, performed using the same basis sets as for the DFT methods. The results obtained employing composite chemical methods (G4, CBS-QB3 and W1BD) were also used for the comparisons, as well as the experimental results when they are available. The results obtained show that error compensation is the key for successful description of molecular properties (geometries and energies) by carefully selecting method and basis sets. In general, expansion of the one-electron basis set to the limit of completeness does not improve results at the DFT level, but just the opposite. The enthalpies of formation calculated at the CCSD(T)/aug-cc-pV6Z for the species considered are generally in agreement with experimental determinations, and the most accurate derived theoretically up to present. Different sources of error in the calculations are discussed in detail.

Funding

ANII, Pedeciba, CSIC-Udelar

History

Email Address of Submitting Author

oscar.n.ventura@gmail.com

Email Address(es) for Other Author(s)

Mkieninger@gmail.com, ken@fq.edu.uy

Institution

CCBG-DETEMA, Facultad de Química, Universidad de la República

Country

Uruguay

ORCID For Submitting Author

0000-0001-5474-0061

Declaration of Conflict of Interest

No conflict of interest

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