Fig. 1.

(A) Optimized unit cell of Li₃SBF₄, with Li in blue, S in yellow, B in gray, and F in green. The green arrow indicates the C_3v orientational symmetry adopted by the BF₄⁻ tetrahedral unit in the cubic cell. The red outline highlights the pyramidal configuration of Li₃S⁺. (B) Calculated phonon spectra of the studied super-LRAP. The red-colored spectra of Li₃SBF₄ and Li₃OBH₄ show the positions of the q-RUMs in these materials. The modes with large distortion of superhalogen ions are colored in white. (C) HSE06 calculated (partial) DoS of the studied super-LRAP. The Fermi level is set to zero in each case. (D) Calculated radial distribution functions of Li₃SBF₄ using MD trajectory data over 100 ps at 400 and 600 K under ambient pressure. (E) Estimated range of ratio between the ionic conductivity of Li₃SBF₄ and that of Li₃OBH₄ at RT by using the energy of the q-RUMs of these materials in a simple Einstein model. n_LSBF and n_LOBH are the mean phonon occupation numbers at RT T_R of Li₃SBF₄ and Li₃OBH₄, respectively.