Electronic, vibrational and thermodynamic properties of beta-HgS (metacinnabar), HgSe and HgTe

TL;DR

This study uses ab initio methods to analyze the electronic, vibrational, and thermodynamic properties of mercury chalcogenides, revealing their band structures, phonon behaviors, and temperature-dependent specific heat, with implications for their semiconducting or semimetallic nature.

Contribution

The paper provides new ab initio calculations of electronic and phonon properties of beta-HgS, HgSe, and HgTe, including spin-orbit effects and pressure dependence, enhancing understanding of their thermodynamic and electronic behavior.

Findings

HgSe and HgTe have inverted direct band gaps, making them semimetallic.

Beta-HgS is predicted to be semiconducting due to negative spin-orbit splitting.

Calculated specific heat matches experimental data across temperatures.

Abstract

We report ab initio calculations of the electronic band structure and the phonon dispersion relations of the zincblende-type mercury chalcogenides (beta-HgS, HgSe, and HgTe). The latter have been used to evaluate the temperature dependence of the specific heat which has been compared with experimental data. The electronic band structure of these materials has been confirmed to have an inverted direct gap of the alpha-tin type, which makes HgSe and HgTe semimetallic. For beta-HgS, however, our calculations predict a negative spin-orbit splitting which restores semiconducting properties to the material in spite of the inverted gap. We have calculated the spin-orbit induced linear terms in k which appear at the Gamma_8 valence bands. We have also investigated the pressure dependence of the crystal structure and the phonons.