Wannier function localisation using Bloch intrinsic atomic orbitals

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.