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The advancement of science and technology is essential for the progress of nanotechnology, which plays a pivotal role in the development of miniaturized and energy-efficient devices. This investigation delves into the As-doped structures within one-dimensional germanene nanoribbons. Utilizing Density Functional Theory (DFT) in conjunction with the Vienna Ab initio Simulation Package (VASP), the study explores the electro-optical properties of the material influenced by As doping, examining both the doping position and density’s effects. Results indicate As significantly alters the electro-optical characteristics, with the semiconductor structure transitioning to metals in top and valley configurations, while meta and para configurations retain semiconductor properties with an indirect band gap. Analysis of bond length, bond angle, magnetism, formation energy and charge density difference elucidates As’ impact on hexagonal structure stability and electromagnetism properties of the system. Furthermore, a comprehensive investigation of optical properties not only offers insights into material systems but also highlights potential applications in optical communications and sensing technologies.

In this paper, we investigated the structural, elastic, topological-electronic properties as well as optical properties of two half-Heusler (HH) heavy fermions-based compounds: HoPtBi and HoPdBi. We accomplished our calculations in the framework of density functional theory (DFT), based on the full potential linearized augmented plane wave (FP-LAPW). Both compounds are antiferromagnetic (AFM) type-II as reported by experimental data so we carried out our study in the AFM type-II configuration. Considering the spin-orbit coupling, we found that the hydrostatic pressure leads to a phase transition from the trivial semimetal to the topological semimetal (TSM) because of band inversion for HoPdBi with no apparent effect of hydrostatic pressure on the topological phase for HoPtBi. We also studied their optical properties, without and with hydrostatic pressure. The first peak in reflectivity, absorption, optical conductivity spectra and energy loss factor are strongly influenced by the hydrostatic pressure. Both compounds exhibit a considerable first absorption peak in the visible and ultraviolet ranges and they are best candidates for solar cells considered essential in renewable energy.

Endofullerenes M@C₆₀ with M = Li, Na, Ag are considered theoretically at the ab initio level. The electronic structure is calculated to reveal effects of the nature of metal atoms inside C₆₀ upon features of the minimum energy endostructures. The Hartree–Fock and DFT methods with all-electronic (Li and Na) and effective core potential (Ag) basis sets were used admitting an arbitrary symmetry distortion (down to the C₁ point group). All structures display the off-center position of the endoatoms. The charge transfer between metal atoms and the carbon cage is also strongly dependent on the nature of the metals. Ionization potentials and atomic radii are proposed as the basic factors providing properties of the endofullerenes.

The electrical properties of porous graphene (PG) are investigated by using the density functional theory (DFT) with the generalized gradient approximation (GGA). The addition of Boron and nitrogen impurities could change the semiconductor into the $n$ or $p$-type. Results showed that PG had pseudo-metal properties and a direct band gap. Furthermore, adding two impurities resulted in a greater decrease in the energy of the band gap as compared to the other states. In particular, when two impurities were of the boron type, the reduction was more tangible. Moreover, the addition of impurity could also increase the conductivity and pushed the electrical properties toward being a metal.

Karanjin, phytochemical from Pongamia pinnata is reported to be effective against HIV that causes AIDS in humans, however, the delivery of this therapeutic molecule still needs improvement. Hence, this study provides a better understanding of the nonbonded interaction between an anti-HIV drug karanjin and carbon nanotube (CNT) (C56H16). The electronic structure and interaction properties of the molecule karanjin over the surface of CNT were theoretically studied in the gas phase by DFT/B3LYP/6-31G ($d,p$) level of theory for the first time. The UV–Vis spectra and transitions of the karanjin drug, CNT (C56H16) and complex CNT (C-56)/karanjin in gas phase have been calculated by time-dependent density functional theory (TDDFT) for the investigation of adsorption effect. To support our hypothesis, we have performed quantum chemical analysis for CNT (C56H16)/karanjin in water and DMSO solvent. In this process, this CNT (C-56)/karanjin complex enters into affected cell in liquid medium. After that, the drug delivery system CNT (C-56) unloads karanjin at the affected site. The binding character interactive species have been determined by NBO and AIM analysis. The frontier orbital HOMO–LUMO gap, chemical softness, chemical hardness have also been calculated to understand its complete chemical properties. The outcomes from our interaction of drug karanjin with CNT (C56H16) will be instrumental for better drug delivery potential in the upcoming future.

It is predictable that hydrogen gas will be used as the common main energy supply instead of fossil fuels in the near future. Studying hydrogen-production by using hydrogen-rich materials as a source of hydrogen on metal-free catalysts may be worthwhile. We studied the adsorption of ethane, as a hydrogen-rich molecule, on the one, two and three aluminum-doped boron nitride nanotubes using density functional theory. The interactions between any possible sides of ethane and any possible sites on ${\mathrm{\text{Al}}}_B$-doped BNNT were studied. The only adsorption has occurred from the carbon atom side of the ethane molecule on the doped aluminum atom site of the BNNT. After the adsorption process, the possible configurations of the intermediates and transition states to receive the decomposition reaction pathway of the ethane molecule were surveyed. The results showed that the ethane molecule was decomposed only on the two aluminum-doped BNNT to four hydrogen atoms.

The study utilizes the OLCAO-LBFGS-GGA-PBESol method to investigate the structural properties of both doped and undoped brookite TiO₂. Electronic characteristics are explored employing the OLCAO-LBFGS-MGGA-TB09+c approach. Detailed analyses of Density of States (DOS) and Partial Density of States (PDOS) are conducted to understand band structures. Both doped and undoped scenarios exhibit a direct bandgap. Moreover, doping induces a reduction in the bandgap value, enhancing its potential for photovoltaic and photocatalytic applications. The study also establishes a strong agreement between the derived lattice parameters and bandgap for pure brookite TiO₂ and experimental lattice parameters and bandgap value.

Density functional theory (DFT) analyses were carried out to study electronic structures and magnetic properties of Mn- and Cu-doped GaNNS. To investigate the influence of transition metal atoms (TM) on magnetic properties, we substituted Ga atoms with Mn and Cu atoms in different concentrations. Investigation shows that TM leads to electronic structural reconstruction which changes their properties in this way, and plays a significant role in spin polarization. Although the pure nanosheet is a nonmagnetic semiconductor, the doped atoms induce magnetism in the structure. The band gap changes monotonically depending on the concentration of TM atoms. The observed good half-metal ferromagnetism GaNNS:Mn, allows them to be a potential candidate for use in spintronics. The local magnetic moment calculated from Mulliken analyses for the Mn atom is approximately 4.05 $\mu$B.