6533b83afe1ef96bd12a7891

RESEARCH PRODUCT

Electron correlation effects on the calculated 13C NMR spectra of vinyl cations

Jürgen GaussJürgen GaussJohn F. Stanton

subject

Electronic correlationChemistryChemical shiftIsotropyExtrapolationCarbon-13 NMRCondensed Matter PhysicsBiochemistryMolecular physicsSpectral lineComputational chemistryAdditive functionPhysical and Theoretical ChemistryBasis set

description

Abstract A study of calculated 13C NMR chemical shifts in vinyl cations is presented. The sensitivity of predicted isotropic shifts to correlation, basis set and geometry effects is explored. In order to obtain accurate estimates that are reasonably well converged with respect to further improvements in theory, it appears that the CCSD(T) method must be used with a basis of triple-zeta plus polarization quality on the carbon atoms. Second-order many-body perturbation theory performs adequately for all carbons except for that bearing the formal positive charge, while the self-consistent field approximation cannot be relied upon to predict even the correct qualitative ordering in the spectrum. Various extrapolation schemes that assume an approximate additivity of basis set and correlation effects are also explored.

https://doi.org/10.1016/s0166-1280(96)04926-3