Hartree–Fock and density functional complete basis-set (CBS) predicted nuclear shielding anisotropy and shielding tensor components

Complete basis set B3LYP NMR calculations of CDCl3 solvent's water fine spectral details

“…[8,11 -14] The best absolute NMR shielding parameters are obtained from fitting the results of systematic ab initio calculations with correlation-consistent [15,16] or polarization-consistent [17,18] basis sets toward the basis set limit. [13,14,19,20] Such results do not depend on accidental error cancellation and the use of reference molecule. However, the use of correlation-consistent basis sets for complete basis set (CBS) approximation to the Hartree-Fock or Kohn-Sham limit at self consistent field (SCF) and/or density functional theory (DFT) level is not widely recognized.…”

“…Obviously one cannot use the CBS-fitting procedure as a 'black box' and a graphical inspection of the results is essential. [13,14,19] The behavior of calculation results using correlation-consistent basis sets may depend on the density functional, the element, and property studied. [23] For example, the heats of hydrogenation of N 2 , N 2 H 2 , and N 2 H 4 studied with B3LYP and cc-pVxZ (x = 2, 3 and 4)…”

“…[13,14,19,20] The convergence of spin-spin couplings (SSCCs) using conventional and modified cc-p(C)VxZ basis sets for x = 2, 3, 4 and in some cases x = 2, 3, 4 and 5 only, was studied at multiconfiguration self-consistent field (MCSCF) level by Helgaker et al, [26] as well as with modified polarization-consistent basis sets pcJ-n, where n = 0, 1, 2, 3 and 4, was recently reported by Jensen. [18] Among many reports on theoretically predicted SSCC parameters are Hartree-Fock (HF) SCF and MCSCF calculations on water by Casanueva et al, [27] second order polarization propagator approxination (SOPPA) and SOPPA (CCSD) calculations by Enevoldsen et al, [28] DFT and MCSCF studies by Ruden et al, [29] DFT and CCSD studies by Helgaker et al, [30] and DFT predictions of Deng et al [31] However, the fitting of SSCC data obtained in a series of calculations with both correlation-consistent and polarization-consistent families of basis sets toward the basis set limit was not attempted.…”

H2O, H2, HF, F2 and F2O nuclear magnetic shielding constants and indirect nuclear spin–spin coupling constants (SSCCs) in the BHandH/pcJ‐n and BHandH/XZP Kohn–Sham limits

“…CBS estimated BHandH equilibrium proton and oxygen nuclear isotropic shieldings of water (in ppm) calculated using GIAO method and XZP, pcS-n and pcJ-n basis sets too erratic and are omitted from fittings. [11,24,26] The extrapolated lines (3-parameter exponential fits) indicate practically identical performance of the three basis set families in the basis set limit, and there are only minor differences in 17 O isotropic shielding sensitivity to the basis set type (XZP > pcS-n > pcJ-n).…”

“…Further, the detailed studies of nuclear isotropic shielding, shielding anisotropy and its individual components obtained in the basis set limit at HF, DFT and MP2 levels were reported a few years later. [11,24] The CBS approach was also applied successfully in 2006 by Moon and Case [25] for obtaining NMR parameters of small peptides at HF, MP2 and DFT levels of theory. Moreover, in 2007, the performance of cc-pVxZ and pc-n basis sets in predicting NMR parameters of molecular hydrogen and water in the basis set limit at MP2 and CCSD(T) levels was reported.…”