Molecular dynamics simulations with AIREBO potential are performed to investigate the effects of rectangular nanoholes with different areas, aspect ratios (length/width ratios) and orientations on the tensile strength of defective graphene.

The deformation temperature, strain rate, and loading conditions have a significant effect on the deformation behavior and mechanical properties of the Ni/Ni ₃ Al superalloy.

A first-principles study was performed to investigate the adsorption properties of gas molecules (CO, CO₂, NO, and NO₂) on carbon- (C-), nitrogen- (N-), and oxygen-doped (O) borophene. The adsorption energies, adsorption configurations, Mulliken charge population, surface work functions, and density of states (DOS) of the most stable doped borophene/gas-molecule configurations were calculated, and the interaction mechanisms between the gas molecules and the doped borophene were further analyzed. The results indicated that most of the gas molecules exhibited strong chemisorption at the VB site (the center of valley bottom BB bond) of the doped borophene (compared to pristine borophene). Electronic property analysis of the C-doped borophene/CO₂ and the NO₂ adsorption system revealed that there were numerous charge transfers from the C-doped borophene to the CO₂ and NO₂ molecules. This indicated that C-doped borophene was an electron donor, and the CO₂ and NO₂ molecules served as electron acceptors. In contrast to variations in the adsorption energies, electronic properties, and surface work functions of the different gas, C-, N-, and O-doped borophene adsorption systems, we concluded that the C-, N-, and O-doped borophene materials will improve the sensitivity of CO, CO₂, and NO₂ molecule; this improvement of adsorption properties indicated that C-, N-, and O-doped borophene materials are excellent candidates for surface work functions transistor to detect gas molecules.

This study evaluated the electronic structure and optical properties of Fe-doped, Ni-doped, and (Fe,Ni)-co-doped Cu₂ZnSnS₄ through the first-principles pseudopotential plane-wave method based on density functional theory. The results indicated that Fe single-doping and Ni single-doping Cu₂ZnSnS₄ can reduce the charge transfer number of adjacent S atoms, enhancing covalent bonding in Fe–S and Ni–S bonds and reducing the bond length, lattice constants a and c, and unit cell volume v. The formation energies for Fe-doping, Ni-doping, and (Fe,Ni)-co-doping were 1.0 eV, 0.58 eV, and 0.78 eV, respectively. Both Fe and Ni-doping introduced 3d electrons near the Fermi level, resulting in new impurity levels and a gradual decrease in the band gap of Cu₂ZnSnS₄ from 0.16 eV. The conduction band density of Cu₂ZnSnS₄ was primarilycontributed by Sn 5s, Sn 5p, and a portion of S 3p orbital electrons, whereas the valence band density mainly stemmed from Cu 3d, Sn 5p, and S 3p orbital electrons. Fe and Ni-doping also partly contributed to the 3d layer electrons. In the case of (Fe,Ni)-co-doping, the maximum static dielectric constant was 100.49, and the dielectric peak shifted toward the low-energy direction in the presence of both Fe and Ni. Within the visible light range, Fe-doping, Ni-doping, and (Fe,Ni)-co-doping in Cu₂ZnSnS₄ exhibited absorption coefficients greater than 10⁴ cm⁻¹, with the maximum absorption coefficient being 1.6 × 10⁵ cm⁻¹ in the case of (Fe,Ni)-co-doping. In the energy range from 1.5 to 6.3 eV, the reflectivity of Cu₂ZnSnS₄ doped with Fe, Ni, or both was lower than 30%. Notably, a high conductivity peak at 1.9 eV indicated that Cu₂ZnSnS₄ possesses good photoconductivity in the visible range. Fe-doping and Ni-doping resulted in a slight shift of the conductance peak position towardthe low-energy direction, accompanied by an increase in the peak value.

We investigated the electronic and magnetic properties of bulk and monolayer CrSi₂ using first-principle methods based on spin-polarized density functional theory. The phonon dispersion, electronic structures, and magnetism of bulk and monolayer CrSi₂ were scientifically studied. Calculated phonon dispersion curves indicated that both bulk and monolayer CrSi₂ were structurally stable. Our calculations revealed that bulk CrSi₂ was an indirect gap nonmagnetic semiconductor, with 0.376 eV band gap. However, monolayer CrSi₂ had metallic and ferromagnetic (FM) characters. Both surface and confinement effects played an important role in the metallic behavior of monolayer CrSi₂. In addition, we also calculated the magnetic moment of unit cell of 2D multilayer CrSi₂ nanosheets with different layers. The results showed that magnetism of CrSi₂ nanosheets was attributed to band energy between layers, quantum size, and surface effects.