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 by hybrid functionals, which costs lots of computational resources. To save 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, concurrently calculate the Fermi-contact shifts on two nuclei (⁶Li and ¹⁷O) to predict the optimal U_eff. The optimal U_eff is also helpful to the quadrupolar coupling constant C_Q, g-factor, band structure and density of states.