Pressure dependent topological, superconducting, optoelectronic and thermophysical properties of Ta2Se chalcogenide: Theoretical insights

TL;DR

This study uses first-principles calculations to explore how hydrostatic pressure affects the structural, electronic, optical, and superconducting properties of layered Ta2Se, revealing pressure-induced enhancements and stability.

Contribution

It provides a comprehensive theoretical analysis of pressure effects on Ta2Se, linking structural, electronic, optical, and superconducting properties within a unified framework.

Findings

Pressure increases lattice stiffness and melting temperature.

Ta2Se remains metallic with pressure, showing band broadening and Fermi surface changes.

Superconducting transition temperature is around 3.9 K, tunable by pressure.

Abstract

Tetragonal Ta2Se is a layered, Ta-rich chalcogenide that departs from conventional MX2 transition-metal dichalcogenides by hosting dense Ta-Ta networks capped by Se square-net layers. Here, we present a unified first-principles investigation of hydrostatic-pressure tuning in Ta2Se from 0 to 10 GPa, connecting the structural response, mechanical stability, thermophysical indicators, bonding evolution, electronic and optical behavior, lattice dynamics and superconductivity within a single framework. The derived thermophysical descriptors corroborate a pressure-stiffened lattice: density increases, Debye temperature rises, melting temperature is elevated and minimum thermal conductivity increases, whereas the Gr\"uneisen parameter remains within a narrow window, suggesting no anomalous anharmonic softening. Bond population metrics and electron-density-difference analysis revealed a mixed metallic-covalent bonding picture dominated by a robust Ta-Ta metallic backbone, accompanied by pressure-strengthened Ta-Se hybridization. Electronic-structure calculations show persistent metallicity under compression; pressure broadens bands, reduces density of states at the Fermi level, reshapes the Fermi surface and points to a possible Lifshitz-type reconstruction without symmetry breaking. The optical response remained metallic with Drude-like low-energy behavior and pressure-tunable spectral features. The phonon dispersions exhibit no imaginary modes, confirming dynamical stability. Electron-phonon coupling calculations classify Ta2Se as a weak-coupling, phonon-mediated superconductor with Tc around 3.9 K, consistent with available experiments and establish pressure as a practical control knob for stability and superconductivity-relevant descriptors in this metal-rich layered platform.