title: Empirical and DFT GIAO quantum-mechanical methods of (13)C chemical shifts prediction: competitors or collaborators?
abstract: The accuracy of (13)C chemical shift prediction by both DFT GIAO quantum-mechanical (QM) and empirical methods was compared using 205 structures for which experimental and QM-calculated chemical shifts were published in the literature. For these structures, (13)C chemical shifts were calculated using HOSE code and neural network (NN) algorithms developed within our laboratory. In total, 2531 chemical shifts were analyzed and statistically processed. It has been shown that, in general, QM methods are capable of providing similar but inferior accuracy to the empirical approaches, but quite frequently they give larger mean average error values. For the structural set examined in this work, the following mean absolute errors (MAEs) were found: MAE(HOSE) = 1.58 ppm, MAE(NN) = 1.91 ppm and MAE(QM) = 3.29 ppm. A strategy of combined application of both the empirical and DFT GIAO approaches is suggested. The strategy could provide a synergistic effect if the advantages intrinsic to each method are exploited.
authors.affiliation: Advanced Chemistry Development, Moscow Department, 6 Akademik Bakulev St, 117513 Moscow, Russian Federation.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Elyashberg
authors.forename: Kirill
authors.initials: K
authors.lastname: Blinov
authors.forename: Yegor
authors.initials: Y
authors.lastname: Smurnyy
authors.forename: Tatiana
authors.initials: T
authors.lastname: Churanova
authors.forename: Antony
authors.initials: A
authors.lastname: Williams
mesh_terms: D002247:Carbon Isotopes; D003198:Computer Simulation; D036262:Empirical Research; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D008956:Models, Chemical; D011789:Quantum Theory; D012015:Reference Standards
chemical_list: D002247:Carbon Isotopes