Ab initio Wannier-function-based correlated calculations of Born effective charges of crystalline Li$_{2}$O and LiCl

TL;DR

This study employs a new ab initio Wannier-function approach to accurately calculate Born effective charges in Li₂O and LiCl, resolving previous experimental controversies and confirming ionic bonding characteristics.

Contribution

The paper introduces a Wannier-function-based methodology for correlated calculations of Born effective charges, providing improved agreement with experiments and clarifying previous experimental ambiguities.

Findings

Calculated Born charges agree with experimental data.

Resolved controversy regarding Li₂O's effective charge.

Confirmed ionic bonding in Li₂O through Mulliken analysis.

Abstract

In this paper we have used our recently developed ab initio Wannier-function-based methodology to perform extensive Hartree-Fock and correlated calculations on Li$_{2}$O and LiCl to compute their Born effective charges. Results thus obtained are in very good agreement with the experiments. In particular, for the case of Li$_{2}$O, we resolve a controversy originating in the experiment of Osaka and Shindo {[}Solid State Commun. 51 (1984) 421] who had predicted the effective charge of Li ions to be in the range 0.58--0.61, a value much smaller compared to its nominal value of unity, thereby, suggesting that the bonding in the material could be partially covalent. We demonstrate that effective charge computed by Osaka and Shindo is the Szigeti charge, and once the Born charge is computed, it is in excellent agreement with our computed value. Mulliken population analysis of Li$_{2}$O also confirms ionic nature of the bonding in the substance.