Assessment of Density Functionals for Predicting One-Bond Carbon-Hydrogen NMR Spin-Spin Coupling Constants.

We benchmark the performance of 20 approximate density functionals for the calculation of one-bond carbon-hydrogen NMR spin-spin coupling constants (SSCCs). These functionals range from the simplest local-spin density approximation to novel meta-generalized gradient approximation and hybrid density functionals. Our testing set consists of 72 diverse molecules that represent multiple types of hybridization of the carbon atom corresponding to 96 experimentally measured one-bond carbon-hydrogen SSCCs. Our results indicate that generalized gradient approximations perform best for this type of coupling.