where q i represents the charge and σi the ionic radius of the i-th atom. The parameters A ij , P ij and C ij describe the overlap-repulsion energy of the electron clouds, the average charge dipole interactions, and the dispersion constant between the ion pairs i and j, respectively. The Vashishta-Rahman potential has a softer overlap repulsion (1/r n , where n = 11, 9, or 7 for cation-cation, cationanion, and anion-anion pairs, respectively), particularly between the anion-anion pairs. The inter-atomic parameters used in this study are listed in Table . Some of the parameters have already been reported . The parameters that are unavailable in the literature were determined using empirical fitting to attain the experimentally reported bond lengths (Li-O, Fe-O, and O-O) of Na 2 LiFeTeO 6 . The details of the empirical fitting methods are as follows: The non-identical brucite-like octahedral framework along the c-axis is retained by refining the Li-Na, Fe-Na, and Te-Na pairs and the Na-O parameters were refined to represent the conductivity.