Semi-empirical Hartree-Fock simulations of lattice relaxation and effective interactions in Li-doped KTaO₃

As an extension of our previous study of a single Li impurity in KTaO₃, we applied the semi-empirical method of the intermediate neglect of differential overlap (INDO) based on the Hartree-Fock formalism for the study of interaction between Li impurities in KTaO₃. The calculations have been done using the 6×3×3 supercells (containing up to 270 atoms), and the possible implications of limited supercell size discussed. The comparison is made with the data available from the shell model calculations by Stachiotti et al. The interacting energy of two Li impurities is estimated as a function of their relative distance and orientation. The lattice relaxation effect is studied for the case of nearest Li impurities and found to enhance the interaction energy from 62 to 105 meV.