New efficient pecS- ( = 1, 2) basis sets for quantum chemical calculations of P NMR chemical shifts

The basis sets that are used in the quantum chemical calculations of 31 P NMR chemical shifts have always been one of the most important factors of accuracy. Regardless of what high-quality approach is employed, using basis sets of insufficient flexibility in the important angular regions may give poor results and lead to misassignments of the signals in the 31 P NMR spectra. In this work, it was found that the existing nonrelativistic basis sets for phosphorus atom of double- and triple- ζ quality, specialized for the 31 P NMR chemical shifts calculations, are essentially undersaturated in the d -angular space that occurred to play a significant role in the overall accuracy of these calculations. This problem has been thoroughly investigated, and new pecS- n ( n = 1, 2) basis sets for phosphorus chemical shifts calculations were proposed. The exponents and contraction coefficients for the pecS- n basis sets were generated with the property-energy consistent method that has been introduced in our earlier paper, and has been proven useful in the creation of efficient property-oriented basis sets. New basis sets were optimized using the GIAO-DFT method with the B97-2 functional. Extensive benchmark calculations showed that the pecS-1 and pecS-2 basis sets provide very good accuracy, characterized by the corrected mean absolute percentage errors against the experiment of about 7.03 and 4.42 ppm, respectively. In particular, the accuracy of 31 P NMR chemical shifts calculations achieved with the pecS-2 basis set is one of the most favorable accuracies for today. We believe that our new pecS- n ( n = 1, 2) basis sets for phosphorus atom will prove useful in modern large-scale quantum chemical calculations of 31 P NMR chemical shifts. New efficient pecS- n ( n = 1, 2) basis sets for phosphorus atom have been generated with modern PEC method. The new basis sets are moderate in size and demonstrate very good accuracy in the quantum chemical calculations of 31 P NMR chemical shifts.