Beyond Chemical Accuracy for Alkane Thermochemistry: The DHthermo Approach.

摘要: The so-called protobranching phenomenon, that is the greater stability of branched alkanes with respect to their linear isomers, represents an interesting challenge for approaches based on density functional theory (DFT), since it requires a balanced description several electronic effects, including (intramolecular) dispersion forces. Here, we investigate this problem using protocol recently developed double-hybrid functionals and small basis set, DH-SVPD, suited noncovalent interactions. energies bond separation reactions (BSR), defined isodesmic principle, are taken as reference properties evaluation 15 DFT approaches. obtained results show error lower than "chemical accuracy" (<1.0 kcal/mol) can be by proposed both relative reaction enthalpies. These then verified standard BSR36 data set support proposition our computational protocol, named DHthermo, where any DH functional, such PBE-QIDH or B2PLYP, provides accurate when coupled empirical correction DH-SVPD set. This not only gives subchemical accuracy thermochemistry but extremely easy use common quantum-chemistry codes.