Diffuse and doubly split atom occupation in hexagonal LiBH4

A theoretical study has been performed to explain problems in the structural analysis of LiBH4 and its recently discovered superionic conductance. First-principles molecular dynamics simulations for the high temperature (hexagonal) phase show doubly split and diffuse occupation in the c-direction at Li and B sites, respectively. Li hopping within the split sites and libration of H atoms are also found. These dynamics are supported by the Rietveld analysis showing atomic displacement ellipsoids for Li and B atoms.