The importance of solvent effects in calculations of NMR coupling constants at the doubles corrected Higher Random-Phase Approximation

In this work, 242 NMR spin-spin coupling constants (SSCC) in 20 molecules have been calculated either with correlated wave-function methods, SOPPA and HRPA(D), or with density functional theory based on the B3LYP, BHandH, or PBE0 functionals. The calculations were carried out with and without treatment of solvation via a polarizable continuum model in both the geometry optimization step and/or the SSCC calculation, and thereby four series of calculations have been considered (the full-vacuum calculation, the full-solvent calculation, and the two cross combinations). The results were compared with the experimental results measured in a solvent. With the goal of reproducing experimental values, we find that the performance of the PBE0 and BHandH SSCCs improves upon including solvation effects. On the other hand, the quality of the B3LYP SSCCs worsens with the inclusion of solvation. The performance of the SOPPA and HRPA(D) calculations was almost not affected by whether solvation was included. We find the PBE0-based calculations of the spin-spin coupling constants to have the best agreement with the experimental data.