Semiempirical Hartree-Fock calculations for pure and Li-doped KTaO3

TL;DR

This paper applies semiempirical Hartree-Fock calculations to study pure KTaO_3 and Li-doped KTaO_3, focusing on lattice relaxations, impurity effects, and comparison with experimental data.

Contribution

It extends previous work on KNbO_3 by parameterizing and analyzing KTaO_3 with Li impurities using semiempirical Hartree-Fock methods.

Findings

Li displacements and relaxation energies match experimental estimates.

Lattice relaxation extent around Li impurities characterized.

Different neighbor contributions to relaxation energy analyzed.

Abstract

In extension of our previous study of KNbO_3 by the semiempirical Hartree-Fock method we present parameterization and total-energy results for non-ferroelectric KTaO_3 as a pure crystal (concentrating on the frozen phonon calculations) and that with Li impurities. The magnitudes of off-center Li displacements and the relaxation energies related to re-orientation of Li are calculated and compared with experimental estimates and earlier calculation results. The spatial extent of lattice relaxation around Li impurities and contributions from different neighbors to the relaxation energy are discussed.