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Motivated by the recent advances in stanene based devices for potential application such as superior gas sensors and electronic devices, we systematically investigated the structural configurations, adsorption energies and charge transfer of organic molecules (OM) on stanene sensors using first-principles calculations. The results show that aniline (C6H7N) and chlorobenzene (C6H5Cl) act as charge acceptors and are chemisorbed on stanene with sizable adsorption energies for the most stable OM/stanene systems. In particular, C6H7N/stanene and C6H5Cl/stanene systems can open the band gaps with 114.3 and 5.0 meV, respectively. Moreover, adsorption energies, charge transfer and band gaps of OM/stanene systems under external electric field can change dramatically, which indicates that external factors on stanene are highly preferred. Our results provide a theoretical basis for the application of stanene in highly sensitive sensor devices.

Through density-functional theory calculations, we investigated the half-metallic properties of semichlorinated gallium nitride (Cl–GaN) nanosheets (NSs) under an electric field F . The results show that the electric field can modulate Cl–GaN NSs efficiently from ferromagnetic metals to half-metals. More interestingly, under a broad range of electric field intensity (−0.10~−1.30 V/A), Cl–GaN NSs have the excellently half-metallic properties with the band gaps (3.71–0.96 eV) and maximal half-metallic gaps with 0.30 eV in spin-up states and metallic behaviors in spin-down states. Moreover, the total magnetic moment decreases (increases) depending on the negative (positive) F , mainly induced by the unpaired N atoms. Our studies demonstrate that the electronic and magnetic properties of GaN NSs can be delicately tuned by the combined surface modification and electric field, indicating the potential of GaN NSs for developing high-performance spintronic nanodevices.

The effects of intertube additional atoms on the sliding behaviors of double-walled carbon nanotubes (DWCNTs) are investigated using molecular dynamics (MD) simulation method. The interaction between carbon atoms is modeled using the second-generation reactive empirical bond-order potential coupled with the Lennard—Jones potential. The simulations indicate that intertube additional atoms of DWCNT can significantly enhance the load transfer between neighboring tubes of DWCNT. The improvement in load transfer is guaranteed by the addition of intertube atoms which are covalently bonded to the inner and outer tubes of DWCNT. The results also show that the sliding behaviors of DWCNT are strongly dependent of additional atom numbers. The results presented here demonstrate that the superior mechanical properties of DWCNT can be realized by controlling intertube coupling. The general conclusions derived from this work may be of importance in devising high-performance CNT composites.

The effects of nickel coating on the torsional behaviors of single-walled carbon nanotubes (SWCNTs) subject to torsion motion are investigated using the molecular dynamics (MD) simulation method. The simulation results show that regardless of chirality, defect or radius, nickel coating can considerably enhance the critical torque of SWCNTs. However, by comparing the critical torsion angle between nickel-coated SWCNTs and corresponding pristine SWCNTs, it is found that nickel coating in small-radius nanotubes does induce a reduction in the critical torsion angle. The results also show that the structural failure of nickel coated imperfect (9,0) SWCNT occurs at an obviously higher critical torque in comparison with uncoated (9,0) SWCNT with a vacancy defect. Furthermore, we also find that the critical torque of a short nickel coated SWCNT is bigger than that of a long one, while the critical torsion angle for a short tube is smaller than that for a long one.

The effects of intertube spacing, tube length and wall numbers on the sliding behaviors of multi-walled carbon nanotubes (MWCNTs) are investigated using molecular dynamics (MD) simulation method. The interaction between carbon atoms is modeled using the second-generation reactive empirical bond-order potential coupled with the Lennard-Jones potential. The simulations indicate that, regardless of tube length and wall numbers, small intertube spacing of MWCNT can provides an effective channel for load transfer between tubes, and permits mechanical participation of walls. The results also show that the sliding behaviors of MWCNT are strongly dependent of tube length and wall numbers, especially MWCNT with small intertube spacing. It is observed that small intertube spacing of triple-walled carbon nanotube (TWCNT) result in the formation of intertube sp3 bonds during pullout process. The general conclusions derived from this work may be of importance in devising high-performance carbon nanotube (CNT) composites.

We report molecular dynamics studies of single-walled carbon nanotubes (SWCNT) as a bandage to connect separated SWCNTs for getting structures of random length. The mechanical properties of the connected SWCNT strands with different joint length under axial loads are investigated using the classical molecular dynamics simulations method. The interaction between atoms is modeled using the second-generation of reactive empirical bond-order (REBO) potential coupled with the Lennard–Jones (L–J) potential. The mechanical properties, such as Young's modulus, tensile strength, critical buckling strains and critical buckling loads are determined and presented for SWCNT and connected SWCNT strands. The results indicates that the joints made in this way have relatively high mechanical properties corresponding to that of the ideal SWCNTs.

The effects of amorphous lamella on the crack propagation behavior in crystalline/amorphous (C/A) Mg/Mg–Al nanocomposites under tensile loading are investigated using the molecular dynamics simulation method. The sample with an initial crack of orientation [0001] is considered here. For the nano-monocrystal Mg, the crack growth exhibits brittle cleavage. However, for the C/A Mg/Mg–Al nanocomposites, the 'double hump' behavior can be observed in all the stress–strain curves regardless of the amorphous lamella thickness. The results indicate that the amorphous lamella plays a critical role in the crack deformation, and it can effectively resist the crack propagation. The above mentioned crack deformation behaviors are also disclosed and analyzed in the present work. The results here provide a strategy for designing the high-performance hexagonal-close-packed metal and alloy materials.

The effect of tilt interfaces and layer thickness of Cu/Ni multilayer nanowires on the deformation mechanism are investigated by molecular dynamics simulations. The results indicate that the plasticity of the sample with a 45° tilt angle is much better than the others. The yield stress is found to decrease with increasing the tilt angle and it reaches its lowest value at 33°. Then as the tilt angle continues to increase, the yield strength increases. Furthermore, the studies show that with the decrease of layer thickness, the yield strength gradually decreases. The study also reveals that these different deformation behaviors are associated with the glide of dislocation.

The effects of a twin boundary (TB) on the mechanical properties of two types of bicrystal Al thin films during the nanoimprint process are investigated by using molecular dynamics simulations. The results indicate that for the TB direction parallel to the imprinting direction, the yield stress reaches the maximum for the initial dislocation nucleation when the mould directly imprints to the TB, and the yield stress first decreases with the increase of the marker interval and then increases. However, for the TB direction perpendicular to the imprinting direction, the effect of the TB location to the imprinting forces is very small, and the yield stress is greater than that with the TB direction parallel to the imprinting direction. The results also demonstrate that the direction of the slip dislocations and the deformation of the thin film caused by spring-back are different due to various positions and directions of the TB.

The effects of twin spacing and temperature on the deformation behavior of nanotwinned Al under tensile loading are investigated using a molecular dynamic (MD) simulation method. The result shows that the yield strength of nanotwinned Al decreases with the increase of twin spacing, which is related to the repulsive force between twin boundary and the dislocation. The result also shows that there is no strain-hardening at the yield point. On the contrary, the stress is raised by strain hardening in the plastic stage. In addition, we also investigate the effects of stacking fault thickness and temperature on the yield strength of the Al nanowire. The simulation results indicate that the stacking fault may strengthen the Al nanowire when the thickness of the stacking fault is below a critical value.