Regensburg 2019 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 10: Methods in Computational Materials Modelling (methodological aspects, numerics)

MM 10.8: Talk

Monday, April 1, 2019, 17:45–18:00, H45

Reliable methods for combining tight binding models based on maximally localized Wannier functions — •Jae-Mo Lihm and Cheol-Hwan Park — Department of Physics, Seoul National University, Seoul 08826, Korea

Maximally localized Wannier functions (MLWFs) form a set of localized orthogonal basis functions of a periodic system which accurately represent given Bloch states. [1] MLWFs are commonly used as building blocks for large-scale tight-binding calculations. For example, MLWFs generated from ab initio calculations on the bulk and a thin slab of a given material may be used to construct a tight-binding model for a thicker slab, or a semi-infinite slab. However, the corresponding MLWFs of different systems are not identical to their partners. This discrepancy may cause artifacts in the physical quantities calculated from the combined tight-binding model if not properly taken care of.

In this work, we propose two post-processing methods that correct the differences between the MLWFs in two different systems. First, we describe a minimal correction which is simple and efficient, but fails in complex systems. Next, we propose a more accurate and generally applicable correction method based on the hopping parameters. We demonstrate the utility of our correction methods by applying them to real materials. We also compare the corrected MLWFs with the Wannier functions constructed without maximal localization.

[1] N. Marzari et al., Rev. Mod. Phys. 84, 1419 (2012)