Optimizing the $U_{eff}$ value for DFT+U calculation of paramagnetic solid-state NMR shifts by double Fermi-contact-shift verification

The isotropic chemical shifts can be calculated either by full-electron configuration, or by hybrid functionals, which costs a large amount of computational resources. To save the time, DFT+U could be employed to calculate the isotropic chemical shifts. However, the calculated properties are very sensitive to the Hubbard correction value $U_{eff}$. Here the double Fermi-contact-shift verification approach with DFT+U method is proposed with much higher computational efficiency, that is, simultaneously calculate the Fermi-contact shifts on two nuclei (${}^{6}Li$ and ${}^{17}O$) to predict the optimal $U_{eff}$. The optimal $U_{eff}$ is also helpful to the calculations of quadrupolar coupling constant $C_Q$, $g$-factor, band structure and density of states.