Density Functional Theory Study of the Electronic, Structural, and Optical Properties of ZrS ₂ and ZrSeS: Showcasing a Thorough Analysis Using DFT and DFT+U

High Resolution Image Download MS PowerPoint Slide The electronic, structural, and optical properties of layered transition metal dichalcogenides, ZrS 2 and ZrSeS, with trigonal structures, were comprehensively investigated using density functional theory (DFT). Calculations employed various approximations, including LDA, GGA, PBE+U, and PBE0, within the Quantum ESPRESSO framework. Rigorous convergence tests were conducted to ensure computational accuracy for both materials. The calculated equilibrium lattice constants demonstrate good agreement with existing experimental data, validating the chosen computational methods. Analysis of electronic properties revealed that LDA and GGA significantly underestimate the band gap values; in contrast, PBE+U and PBE0 approaches yielded values consistent with experimental results. Furthermore, the optical properties, including the absorption spectrum, complex dielectric function, refractive index, and static and dynamic polarizability, were thoroughly studied. To ensure accuracy, a scissor-operator correction was applied to the optical spectra to align with corrected electronic transitions. Key energy levels and intensities for significant transitions were identified, and the notable anisotropic behavior of these materials was characterized. By positioning these findings within the most recent 2025 developments in solid-state systems, this study provides a high-fidelity benchmark for the optoelectronic and polarizable response of Zr-based TMDs.