The objective of this study is to design a broadband and wide-angle emitter based on metamaterials with a cut-off wavelength of 2.1 µm to improve the spectral efficiency of thermophotovoltaic emitters. To obtain broadband emission, we conducted the geometric parameter optimization of the number of stacked layers, the inner and outer radii of the nano-rings, and the thickness of the nano-rings. The numerical simulation results showed that the proposed emitter had an average emissivity of 0.97 within the targeted wavelength, which ranged from 0.2 µm to 2.1 µm. In addition, the presented multilayer nano-ring emitter obtained 79.6% spectral efficiency with an InGaAs band gap of 0.6 eV at 1400 K.

In this work, the structural, mechanical, electronic, optical and magnetic properties of the RhNbSb half‐Heusler compound were examined and analyzed using density functional theory (DFT). According to the results, type I atomic arrangement is structurally the most stable for the compound. In all three of its atomic arrangement types, the compound is mechanically stable and ductile according to the analysis of its mechanical properties. Generalized gradient approximation (GGA) + U approach was applied in addition to GGA approach, where U is Hubbard parameter, to increase the accuracy of results in electronic band structure, density of states (DOS), and magnetic moments. Therefore, electronic band structure and DOS calculations demonstrate that the compound exhibits metallic properties in both its type I and type II atomic arrangements with GGA predictions. However, under GGA + U calculations, the compound becomes half metal when in type I but it still reflects metallic nature when in type II. The compound’s half‐metallic nature in type I under the GGA+ U method suggests that it may be a good fit for spintronics applications in this type I of its atomic arrangement. The calculated total magnetic moment of the compound under GGA + U approach exactly fits with Slater–Pauling rule of half‐metallic nature in its type I atomic arrangement, a result that supports half‐metallic nature of the compound in type I atomic arrangement for electronic properties under GGA + U prediction. Furthermore, the compound might be taken into consideration for optoelectronic applications according to the results of computed optical characteristics.

This study explored how temperature and solvent polarity influence the structural, electronic, thermodynamic, and spectroscopic properties of pyrazole, a five-membered aromatic compound known for its biological activities. Semiempirical (PM3), Hartree–Fock (HF/aug-cc-pVDZ), and density functional theory (B3LYP with basis sets 3TO-3G*, 6-31G+ (d, p), 6-311+G(d,p), and aug-cc-pVDZ) methods were employed to examine pyrazole in gas and solvent environments. The findings showed that solvent interactions notably affected the molecular geometry, FT-IR spectra, solvation energy, dipole moments, HOMO–LUMO energy gaps, and reactivity. The HOMO–LUMO gap decreased from 7.0557 eV in the gas phase to 7.000 eV in water. The dipole moment increased with increasing solvent polarity from 2.27 D in the gas phase to 4.51 D in water, while the solvation energy also varied accordingly. As the temperature increased from 100 to 1000 K, the molecular vibrations intensified, altering the thermodynamic properties and reducing the molecular stability. UV–vis spectra revealed redshifts in more polar solvents, indicating changes in π–π* transitions. The charge distribution and reactive sites were analyzed via density of states, electrostatic potential maps, reactivity indices, and Mulliken charges. Overall, this study quantifies how environmental conditions alter pyrazole properties and their suitability for various applications.

Using first-principle DFT calculations (Quantum Espresso), we analyze the structural, electronic, and optical properties of hexagonal V0.5Mo0.5S2ySe2(1−y) alloys (y = 0, 0.25, 0.5, and 0.75). Phonon spectra confirm structural stability, with V/S doping reducing bond lengths, angles, and lattice constants vs pure 2H–MoSe2. Vanadium doping induces a semiconductor-to-metal transition, with GGA (GGA+U) bandgaps of 0.976 (1.156) eV for pristine and 0.326 (1.046) eV for V-doped systems. Increasing sulfur content (fixed x = 0.5) further drives this metallic transition. TD-DFPT-calculated optical properties reveal low extinction coefficients/refractive indices and high reflectivity, suggesting anti-reflective/optical coating applications. The loss function shows redshift at y = 0 but blueshifts at y ≥ 0.25. These tunable properties make the alloys promising for nanoelectronics, IR photodetectors, and optoelectronics.