Pressure driven structural phase transitions and modulations in optical properties of lanthanum nitride: an account from on the fly molecular dynamics and SCF vis-à-vis non-SCF first-principle calculations

Abstract

The paper is focused to explore the pressure induced structural phase transitions and modulations of optical properties of lanthanum nitride (LaN) for the first time with the aid of first-principle density functional theory and Born-Oppenheimer on the fly molecular dynamics calculations. Crystal structures, Gibbs free energies and phonon dispersion spectra of the compound in its various phases under ambient and external pressures have been critically investigated. The key phonon modes responsible for these pressure driven transitions have also been unveiled. Electronic band structures and associated optoelectronic properties of the system have been studied in detail from both the self-consistent field and non-self-consistent field calculations. The early signature of topological insulator for the high pressure phase of LaN has been addressed from the electronic band structure calculations. We believe that this study will not only help for futuristic designs of improved functionalized systems with LaN compound but also can augment their applications such as pressure sensors, pressure conducting switches, dissipationless transistors and in optoelectronic devices.

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].…”