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The potential applications of the cubic phase of CsNbO₃ perovskite have been explored by examining its elastic, electronic, and photocatalytic characteristics using a first-principles approach. The structural robustness when subjected to pressure has been verified by studying the computed elastic constants. Its substantial elastic moduli, hardness, and toughness values propose its suitability for various engineering applications. A transition from flexibility to fragility is observed at pressures exceeding 10GPa. The CsNbO₃ material demonstrates an indirect and narrow band gap, making it a promising candidate in optoelectronic applications. Changes in the band gap due to pressure indicate adjustments in orbital hybridization. The material’s low effective carrier mass and high carrier mobility anticipate favorable electrical conductivity. Assessments of the potentials at the conduction band (CB) and valence band (VB) edges underscore the remarkable capacity of CsNbO₃ for activities such as water-splitting and promoting sustainable energy production.

The electronic and magnetic properties of Be${}_{1-x}$(Gd,Eu,Tb)${}_x$O (with $x$ values of 0.125, 0.25, and 0.375) were systematically investigated using the full-potential linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT). Exchange and correlation potentials were computed employing the generalized gradient approximation (GGA) and GGA plus-modified Becke–Johnson potential (TB-mBJ) approximations. Our findings demonstrate that the incorporation of X into BeO induces magnetism in the compound. Specifically, BeO doped with Gd, Eu, and Tb at $x=0.125,0.25$, and 0.375 exhibits half-metallic behavior, characterized by integer magnetic moments. These results indicate the potential of these compounds to serve as novel half-metallic materials for future spintronics applications, offering exciting prospects in the field.

BaHfS₃ and BaZrS₃, two chalcogenide perovskites, show significant promise for next-generation optoelectronic devices due to their adjustable bandgaps, excellent carrier mobilities, and versatile properties. Using density functional theory (DFT) via the WIEN2k package, this study reveals their bandgap energies of 2.05eV and 1.63eV, respectively, situating them in the visible range and making them suitable for photovoltaic (PV) applications. Additionally, both materials satisfy thermodynamic criteria for hydrogen production through water splitting, confirming their photocatalytic potential. Their thermoelectric performance, measured by the figure of merit (ZT) also indicates moderate potential at elevated temperatures. Strain engineering further enhances the PV performance, where a biaxial compressive strain of −6% boosts power conversion efficiencies (PCEs) by 8.34% for BaHfS₃ and 3.30% for BaZrS₃. For photocatalysis, uniaxial and biaxial strains optimize optical absorption and water-splitting kinetics. Furthermore, the thermoelectric properties slightly improve under strain effect. These findings highlight the multifunctional potential of BaHfS₃ and BaZrS₃ for PV, photocatalytic, and thermoelectric applications, with strain engineering providing a robust strategy for performance optimization.

First-principles investigation of the geometry, electronic band structure, Vickers hardness, thermodynamic and optical properties of three superconducting MAX compounds Nb₂AsC, Nb₂InC and Mo₂GaC have been carried out by the plane-wave pseudopotential method based on density functional theory (DFT) implemented in the CASTEP code. The theoretical Vickers hardness has been studied by means of Mulliken bond population analysis and electronic densities of states. The thermodynamic properties such as the temperature and pressure dependent bulk modulus, Debye temperature, specific heats and thermal expansion coefficient of the three 211 MAX phases are derived from the quasi-harmonic Debye model with phononic effect for the first time. Furthermore, all the optical properties are determined and analyzed for the first time for two different polarization directions. The theoretical findings are compared with relevant experiments (where available) and the various implications are discussed in details.

The effect of Vanadium (V) doping on electronic and optical properties of NiO is discussed. Electronic and optical properties of a 32-atom supercell of V${}_x$Ni${}_{1-x}$O $(x=0.0625)$ obtained from first-principles calculations, performed within density functional theory (DFT), using the generalized gradient approximation (GGA) with the Hubbard potential $U$ were studied and compared to those of a 32-atom supercell of pure NiO. From the electronic structure and complex dielectric function analysis, the V doping causes the reduction of the bandgap by inducing the localized V $t_{2g}$ state in the NiO bandgap region, and the first optical transition for V-doped NiO occurs at a lower frequency than the one for the intrinsic NiO. The bandgap shrinkage to about 2 eV makes NiO when doped with V a potential candidate for visible light range application in photocatalytic applications. The resulting effects on refractive index, reflectivity, absorption, optical conductivity and loss function for V-doped NiO are compared to those of pristine NiO.

Density functional theory (DFT) within Wien2k code is utilized to compute the mechanical, thermal, electronic, magnetic and thermoelectric properties of the cubic spinel CoV₂O₄. The ground state lattice constant of CoV₂O₄ alloy agrees with previous literature. The calculated elastic constants of CoV₂O₄ predict that the present alloy is anisotropic, elastically stable and brittle. Beneficial acoustical applications are expected for the present alloy due to its high calculated Debye temperature and average sound velocities values. The longitudinal and transverse sound velocities modes of vibrations are found maximum along [110] directions compared to [100] and [111] directions. The calculated DOS and band structure show that CoV₂O₄ is electronically stable. The present alloy possesses a total magnetic moment of 12.0 ${\mu }_{\mathrm{\text{B}}}$ and is classified as a half-metallic ferromagnet. CoV₂O₄ shows $n$-type behavior and favors holes as charge carriers. The present alloy owns beneficial thermoelectric properties and can be used in thermoelectric applications.

In this work, we investigated the geometrical structures, electronic and magnetic properties of S sites vacancy defects in heterostructure graphene/molybdenum disulphide ((HS)G/MoS${}_2)$ material by performing first-principles calculations based on spin polarized Density Functional Theory (DFT) method within van der Waals (vdW) corrections (DFT-D2) approach. All the structures are optimized and relaxed by BFGS method using computational tool Quantum ESPRESSO (QE) package. We found that both (HS)G/MoS₂ and S sites vacancy defects in (HS)G/MoS₂ (D1S–(HS)G/MoS₂, U1S–(HS)G/MoS₂, 2S–(HS)G/MoS₂ and 3S–(HS)G/MoS${}_2)$ are stable materials, and atoms in defects structures are more compact than in pristine (HS)G/MoS₂ structure. From band structure calculations, we found that (HS)G/MoS₂, (D1S–(HS)G/MoS₂, U1S–(HS)G/MoS₂, 2S–(HS)G/MoS₂ and 3S–(HS)G/MoS${}_2)$ materials have $n$-type Schottky contact. The Dirac cone is formed in conduction band of the materials mentioned above. The barrier height of Dirac cones from Fermi energy level of (HS)G/MoS₂, (D1S–(HS)G/MoS₂, U1S–(HS)G/MoS₂, 2S–(HS)G/MoS₂ and 3S–(HS)G/MoS${}_2)$ materials have values 0.56eV, 0.62eV, 0.62eV, 0.64eV and 0.65eV, respectively, which means they have metallic properties. To study the magnetic properties of materials, we have carried out DoS and PDoS calculations. We found that (HS)G/MoS₂, D1S–(HS)G/MoS₂ and U1S–(HS)G/MoS₂ materials have non-magnetic properties, and 2S–(HS)G/MoS₂ and 3S–(HS)G/MoS₂ materials have magnetic properties. Therefore, the non-magnetic (HS)G/MoS₂ changes to magnetic 2S–(HS)G/MoS₂ and 3S–(HS)G/MoS₂ materials due to 2S and 3S atoms vacancy defects, respectively, in (HS)G/MoS₂ material. Magnetic moment obtained in 2S–(HS)G/MoS₂ and 3S–(HS)G/MoS₂ materials due to the unequal distribution of up and down spin states of electrons in 2s and 2p orbitals of C atoms; 4p, 4d and 5s orbitals of Mo atoms; and 3s and 3p orbitals of S atoms in structures. Magnetic moment of 2S–(HS)G/MoS₂ and 3S–(HS)G/MoS₂ materials is −0.11${\mu }_B$/cell and $-0.29{\mu }_B$/cell, respectively, and spins of 2p orbital of C atoms, 3p orbital of S atoms and 4d orbital of Mo atoms have dominant role to create magnetism in 2S–(HS)G/MoS₂ and 3S–(HS)G/MoS₂ materials.

The electronic and transport properties of hybrid armchair–zigzag nanostructures, which include right-angles-shaped GNRs, U-shaped GNRs, and patterned nanopores structured GRNs, were studied by the combination of density functional theory and nonequilibrium Green’s function method. The density of state, electron transmission spectra, and molecular orbitals were analyzed. The obtained results show that right-angles-shaped GNRs junctions tend to open a transport gap when the numbers of right-angles are greater than or equal to 4. The gap increases insignificantly as the numbers of right-angles are greater than 4. It implies that the U-shaped GNR junction, corresponding to 4 right-angles structure, is a potential structure for controlling transport gap of GRNs. The transport gap of the U-shaped GNRs decreases as the length of horizontal edge increases. In contrast, the transport gap increases as the high of vertical edge increases. In addition, the patterned nanopore had an enormous influence on the electronic and transport properties though the armchair GNRs junctions, depending on the shape and size of nanopore. This research suggests that designed tailored GNRs based on hybrid armchair–zigzag nanostructures can be used to control the transport gap of graphene. The formation of quasi-bound states at zigzag edges of the hybrid nanostructures plays a key role.

In this study, we have calculated thermoelectric properties as a function of temperature and doping of the most stable phases of ZnO using first-principle calculations combined with semi-classical equation of Boltzmann. The nature of electrical conductivity is determined; the coefficient of Seebeck and figure of merit as a function of a charge carrier concentration of three structures studied are calculated. At high doping concentration, the rocksalt phase shows the best figure of merit.

The linear and nonlinear optical (NLO) properties of 3,5-dinitrobenzoic acid and some benzamide derivatives are determined using density functional theory. The B3LYP levels with a $6-311+G(d,p)$ basis are used to geometrically optimize 3,5-dinitrobenzoic acid with benzamide derivatives (DBBZM, DB1BZM, DB2BZM, DB3BZM, and DB4BZM). The low energy gap value indicates the possibility of intramolecular charge transfer. These calculations clearly show that the studied molecules can be used as attractive future NLO materials. Their first-order hyperpolarizability is found to be in the [$3.479\times 10^{-30}$, $12.843\times 10^{-30}$ esu] range, indicating that they have significant NLO properties. Furthermore, the RDG, AIM, NBO analyses, the MEP, and gap energy are calculated. The presence of intermoleculars O–H$\cdots$O and N–H$\cdots$O is confirmed by a topological feature at the bond critical point, determined by AIM theory and NBO analyses. All of these calculations have been performed in gas phase as well as cyclohexane, toluene, and water solvents in order to demonstrate solvent effect on molecular structure and NLO properties. In a final step, a molecular docking study was performed to understand the structure–activity relationship.

We have done geometry optimization of two conformers of Lantadene series C and D. The fundamental vibrational frequencies with intensity have been done by using B3LYP/6-311G (d, p) method. The complete vibrational assignments of wavenumbers are made on the basis of potential energy distribution (PED). The nonbonding interactions in Lantadenes C and D are calculated by using the same level theory at the bond critical point (BCP). The calculated topological parameters at BCP are utilized to determine the nature and strength of interactions. We have also computed HOMO–LUMO gap and plotted frontier orbital HOMO–LUMO surfaces, molecular electrostatic potential surfaces to explain the reactive nature of Lantadenes C and D. The electronic transition spectra UV–Vis spectra of Lantadenes C and D are calculated by using TDDFT theory. The values of hyperpolarizability show a probable use of these compounds in electro-optical applications. The natural bonding orbital theory is utilized to calculate transition of electron from donor to acceptor which is very useful to describe nonbonding as well as bonding interactions. The calculated value of Log $P$ and Log $S$ for Lantadene C Lantadene D established its pharmaceutical behaviors. The biological activity of Lantadenes C and D is also calculated by using PASS online server for $\mathrm{\text{Pa}}>70\%$. The docking of Lantadene C Lantadene D is also performed by using Auto dock with predicted drug by Swiss dock online server.

Due to their strong molecular hyperpolarizability, organic push–pull materials are gaining interest for nonlinear optical applications. We were able to characterize the intramolecular charge transfer and the distribution of the electron cloud within the molecular unit by exciting these materials under the influence of an electric field. The series products of conjugated monomers derived from acrylo–azobenzene containing in the para position the attracting groups (–H, –NO₂, –COOC₂H₅, –SO₃H and –COOH) exhibit good nonlinear optical activity. We computed the nonlinear optical characteristics of these compounds as well as exploiting the theoretical calculations of DFT and AM1 to determine their hyperpolarizabilities. Besides, we investigated the increase in hyperpolarizability in the push–pull model of organic compounds under the effect of the strength of attracting groups, the existence of the conjugated $\pi$-electron and the azo bridge.