Pressure induced structural phase transitions of technologically significant mercurous chloride at room temperature: An account from first-principle DFT and Born–Oppenheimer molecular dynamics studies

Abstract

This paper reports for the first time an in-depth study based on first-principle calculations to unveil the underlying physics that governs the pressure induced structural phase transitions of Hg2Cl2 compound at room temperature. The phonon dispersion relations and phonon density of states have been critically explored for the tetragonal and orthorhombic phases of the compound to unveil the phonon modes associated with the phase transitions. The nature of the phase transition whether it is “displacive” or of “order–disorder” type has also been explored. We believe that the present study based on density functional theory and Born–Oppenheimer molecular dynamics calculations will help understand the underlying physics behind the above referred phase transitions and the anisotropic behavior of the compound, which in turn bears technologically significant relevance for its applications in optoelectronic devices, acousto-optic tunable filters, and in fiber-optic communication systems.

Strain induced modulations in the thermoelectric properties of 2D SiH and GeH monolayers: insights from first-principle calculations

“…Closer observations of figure 12 further reveal that the ZA acoustic phonon modes of both the compounds get soften (harden) along M-K and K-Γ high symmetry directions for compressive (tensile) strain in contrast to their respective unstrained counterparts (vide supra, figure 4). Softening and hardening of phonon modes are linked with the decreasing and increasing of phonon frequencies under external perturbations [66][67][68]. The softening and hardening of ZA phonon modes occur due to the influence of atomic coordination on the surface of 2D systems in general [69].…”