Vibrational and dielectric properties of the bulk transition metal dichalcogenides

TL;DR

This study systematically investigates the vibrational and dielectric properties of bulk transition metal dichalcogenides using density functional theory, highlighting the importance of dispersion corrections and confirming the minor role of spin-orbit interaction.

Contribution

It provides a comprehensive analysis of vibrational and dielectric properties across multiple materials, emphasizing the significance of dispersion corrections in modeling.

Findings

Dispersion corrections are crucial for accurate interatomic force constants.

Spin-orbit interaction has a minor effect on these properties.

Results align well with experimental Raman spectra.

Abstract

Interest in the bulk transition metal dichalcogenides for their electronic, photovoltaic, and optical properties has grown and led to their use in many technological applications. We present a systematic investigation of their interlinked vibrational and dielectric properties, using density functional theory and density functional perturbation theory, studying the effects of the spin-orbit interaction and of the long-range e$^-$- e$^-$ correlation as part of our investigation. This study confirms that the spin-orbit interaction plays a small role in these physical properties, while the direct contribution of dispersion corrections is of crucial importance in the description of the interatomic force constants. Here, our analysis of the structural and vibrational properties, including the Raman spectra, compare well to experimental measurement. Three materials with different point groups are showcased and data trends on the full set of fifteen existing hexagonal, trigonal, and triclinic materials are demonstrated. This overall picture will enable the modeling of devices composed of these materials for novel applications.