Computational modeling of the structure and the ionic conductivity of the solid electrolyte materials Li$_3$AsS$_4$ and its Ge substitutions*

Oak Ridge National Laboratory (G. Sahu et al.)\footnote{J. Matter. Chem. A. 2014, {\bf{2}}, 10396} reported that the substitution of Ge into Li$_3$AsS$_4$ leads to the composition Li$_{3.334}$Ge$_{0.334}$As$_{0.666}$S$_4$ with impressively high ionic conductivity . We use ab initio calculations to examine the structural relationships and the ionic conductivity mechanisms for pure Li$_3$AsS$_4$, Li$_{3.334}$Ge$_{0.334}$As$_{0.666}$S$_4$, and other compositions of these electrolytes.