Maximally localized Wannier functions in LaMnO3 within PBE+U, hybrid functionals, and partially self-consistent GW: an efficient route to construct ab-initio tight-binding parameters for e_g perovskites

TL;DR

This paper develops an efficient method to construct maximally localized Wannier functions for LaMnO3 using various computational approaches, enabling accurate tight-binding models for e_g perovskites.

Contribution

It introduces a new interface and methodology to derive tight-binding parameters from ab initio calculations for complex correlated materials.

Findings

TB parameters vary with the exchange-correlation method used

Explicit and implicit electron-electron interaction models produce consistent band dispersions

The derived TB models accurately reproduce ab initio and MLWF band structures

Abstract

Using the newly developed VASP2WANNIER90 interface we have constructed maximally localized Wannier functions (MLWFs) for the e_g states of the prototypical Jahn-Teller magnetic perovskite LaMnO3 at different levels of approximation for the exchange-correlation kernel. These include conventional density functional theory (DFT) with and without additional on-site Hubbard U term, hybrid-DFT, and partially self-consistent GW. By suitably mapping the MLWFs onto an effective e_g tight-binding (TB) Hamiltonian we have computed a complete set of TB parameters which should serve as guidance for more elaborate treatments of correlation effects in effective Hamiltonian-based approaches. The method-dependent changes of the calculated TB parameters and their interplay with the electron-electron (el-el) interaction term are discussed and interpreted. We discuss two alternative model parameterizations: one in which the effects of the el-el interaction are implicitly incorporated in the otherwise "noninteracting" TB parameters, and a second where we include an explicit mean-field el-el interaction term in the TB Hamiltonian. Both models yield a set of tabulated TB parameters which provide the band dispersion in excellent agreement with the underlying ab initio and MLWF bands.