Lattice dynamics in the conformational environment of multilayered hexagonal boron nitride (h-BN) conveys to peculiar infrared optical responses

TL;DR

This paper demonstrates how simplified structural models combined with density functional theory can reveal stacking configurations in layered materials like h-BN through infrared spectroscopy, offering a less complex alternative to advanced characterization techniques.

Contribution

The study introduces a method using effective charge densities and lattice dynamics modeling to determine stacking arrangements in layered materials from infrared spectra.

Findings

Effective charge densities can distinguish stacking variants.

Infrared spectra reflect stacking configurations.

Method applicable to other layered materials.

Abstract

Stacking mismatches in hexagonal boron nitride (h-BN) nanostructures affect their photonic, mechanical, and thermal properties. To access information about the stacked configuration of layered ensembles, highly sophisticated techniques like X-ray photoemission spectroscopy or electron microscopy are necessary. Here, instead, by taking advantage of the geometrical and chemical nature of h-BN, we show how simple structural models, based on shortened interplanar distances, can produce effective charge densities. Accounting these in the non-analytical part of the lattice dynamical description makes it possible to access information about the composition of differently stacked variants in experimental samples characterized by infrared spectroscopy. The results are obtained by density functional theory and confirmed by various functionals and pseudopotential approximations. Even though the method is shown on h-BN, the conclusions are more general and show how effective dielectric models can be considered as valuable theoretical pathways for the vibrational structure of any layered material.