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Validation of DFT‐Based Methods for Predicting Qualitative Thermochemistry of Large Polyaromatics
Author(s) -
Hemelsoet Karen,
De Vleeschouwer Freija,
Van Speybroeck Veronique,
De Proft Frank,
Geerlings Paul,
Waroquier Michel
Publication year - 2011
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201000788
Subject(s) - thermochemistry , delocalized electron , density functional theory , chemistry , van der waals force , unpaired electron , dissociation (chemistry) , computational chemistry , bond dissociation energy , radical , basis set , chemical physics , molecule , organic chemistry
We present a validation of computationally efficient density functional‐based methods for the reproduction of relative bond dissociation energies of large polyaromatic hydrocarbons. Through the calculation of intrinsic radical stabilities and the computation of spin densities, the extent of delocalization of the unpaired electron in the benzylic radicals is examined. We focus on the influence of the level of theory choice applied for the geometry optimization and the role of van der Waals corrections on thermochemical properties. The dispersion effects mainly influence the energetics, causing a small upward shift of the bond dissociation energies. The long‐range corrected CAM‐B3LYP functional does not improve the traditional B3LYP results for the geometry description of the large delocalized radicals, however a non‐negligible influence was encountered when applied for the energetics. It is reported that the f polarization functions present in the 6‐311+G(3df,2p) basis set lead to an erroneous trend when combined with the B2PLYP functional for the computation of the single point energies.