Wannier function localisation using Bloch intrinsic atomic orbitals

TL;DR

This paper introduces a method to localize Wannier functions in crystals using an extension of the IAO approach, including a diabatic phase alignment step, improving localization especially for core bands.

Contribution

It presents a novel Wannierisation technique with phase alignment, enhancing localization and initial guess quality for solid state systems.

Findings

Effective localization of Wannier functions in various solids.

Diabatic phase alignment improves core band localization.

Partial charges align with chemical intuition in surface adsorption examples.

Abstract

We extend the Intrinsic Atomic Orbital (IAO) method for localisation of molecular orbitals to calculate well-localised generalised Wannier functions in crystals using the Pipek--Mezey locality metric. We furthermore present a one-shot diabatic Wannierisation procedure that aligns the phases of the Bloch functions, providing immediate Wannier localisation, which serves as an excellent initial guess for optimisation. We test our Wannier localisation implementation on a number of solid state systems, highlighting the effectiveness of the diabatic preparation, especially for localising core bands. Partial charges of Wannier functions generated using Bloch IAOs align well with chemical intuition, which we demonstrate through the example of adsorption of CO on a MgO surface.