Performance of DFT for²⁹Si NMR chemical shifts of silanes

The predictive power of DFT, HF, and MP2 ²⁹Si NMR chemical shift calculations for silane molecules, including fluoro- and methylsilanes (Si_nH_2n+2 (n = 1, ..., 5), Si_nF_2n+2 (n = 1, ..., 3), and SiH_mX_4-m (X = F, CH₃)) is compared. A systematic accumulation of error proportional to the number of hydrogen neighbors to silicon sites is observed for DFT for all applied exchange-correlation functionals, whereas MP2 is not affected by this problem. A proposed empirical correction scheme for DFT provides excellent agreement with experiment with any exchange-correlation functional employed in this study.