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Shortfall of B3LYP in Reproducing NMR J CH Couplings in Some Isomeric Epoxy Structures with Strong Stereoelectronic Effects: A Benchmark Study on DFT Functionals
Author(s) -
Adamson Jasper,
Nazarski Ryszard B.,
Jarvet Jüri,
Pehk Tõnis,
Aav Riina
Publication year - 2018
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.201701125
Subject(s) - chemistry , density functional theory , context (archaeology) , computational chemistry , coupling constant , basis set , electron density , electron , physics , quantum mechanics , paleontology , biology
Abstract Unprecedented scatter plots of calculated versus measured NMR 2,3 J CH coupling constants in six densely oxygen functionalized epoxides are found with some B3LYP protocols, an effect attributed to stereoelectronic effects. Hence, 26 other exchange‐correlation density functionals (xc DFs) are benchmarked in this work. Very good results are achieved with mPW1PW91 and PBE0 in conjunction with the pcJ‐1 basis set (BS) of moderate size. A thorough statistical analysis of 53 relationships between the predicted and observed 2,3 J CH datasets is presented. The effects of some xc DFs, including their x and c parts, and BSs on the calculation results are discussed, also in the context of DFT modeling of electron‐density distributions. Moreover, related 1 J CH datasets predicted with 11 different DF methods are considered and compared with the experimental data. Finally, some proposals for further improvement of existing DFs based on the available n J CH ( n= 1–3) values are briefly outlined, in line with recent results on the DFT electron densities.