Calculation of chemical bonds and diffusion path of Li ion in (LaLi)Ti 2 O 6 by DV-Xα cluster method

The chemical bonds and lithium diffusion of La 4/3− y Li 3 y Ti 2 O 6 ( y = 0.21) were investigated by using the DV-Xα cluster method. The cluster model used is the formula La 8 Li 2 Ti 2 O 11 . A Li ion was moved on the ab plane at z = 1/2. The Na ion was moved along the x axis in the cluster model La 8 Na 2 Ti 2 O 11 for comparison. The total bond overlap population (BOP) between the moving Li ion and the other ions was calculated on the ab plane at z = 1/2. The total BOP of the Li ion along the x axis increased near the oxygen ion site, whereas the BOP of the Na ion decreased. The decrease in total BOP indicates the decrease in covalent interaction between the Na and the other ions. The change of the net charge of the Li ion was almost the same as that of the Na ion. This suggests that the smaller change of covalent interaction in the mobile Li ion determines the diffusion path of Li ion.