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Abstract: The molecular dynamics (MD) simulations have been utilized to investigate the strain effect on the polarization distribution and piezoelectric coefficient of the ice nanotube (ice-NT) with odd side faces. It is found that the polarization of the system increases under the compressive strain, and decreases with the tensile strain. The piezoelectric coefficient is about 1.3C/m2 for a single 〈5, 0〉 ice-NT with its diameter of 4.34Å, which is superior to BaTiO3 nanowire, the ferroelectricity of the latter with the same diameter has been vanished owning to the depolarization effect. We have also considered the axial strain energy under the different strains, and found that most of the strain energy in the compressive process seems larger than that of the stretching case. [Copyright &y& Elsevier]

Using the classical molecular dynamics method, we have investigated the structure and behavior of the confined water in (20, 0) and (19, 0) single-walled carbon nanotubes (SWCNs). It has been found that several kinds of the double-walled ice nanotubes (Ice-NTs) can indeed be obtained, depending on the diameter of confined SWCNs and the axial pressure. Furthermore, a first-order phase transition-a liquid to double-walled Ice-NT occurs for water in the (20, 0) SWCN at 300 MPa with the melting temperature lower than that of the bulk water. It is noted that water molecules in the tube wall present square lattices at lower pressure, and triangular lattices at higher pressure. More interestingly, high-density nano-ice displays regular chiral double-walled Ice-NT within (19, 0) SWCN at 1.2 GPa, and the outer wall can be considered as (11, 3) Ice-NT resembling the gold nanotube. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rectangular defect can induce the mechanical degradation of the monolayer PtS 2. • Enlarged the defect can promote the mechanical recovery in the same direction. • Enlarged the defect may weaken the mechanical properties in the other direction. Using the classical molecular dynamics simulations, the mechanical properties of the PtS 2 monolayer with rectangular defects have been investigated. Particularly, a counterintuitive defect enlargement method to recover from defect-induced mechanical degradation has been explored. As the rectangular defects are enlarged along the zigzag direction, the uniaxial tension has been firstly applied in the same direction. It's found that the Young's modulus (Y s) increases slightly with the size of the defects. However, both the fracture strain and stress are increased obviously as the length of the rectangular defect increasing, indicating the recovery of the mechanical properties for the defective PtS 2 monolayer. And this degradation recovery could be attributed to the higher degree of geometric asymmetry when the defect being lengthened. Then, the mechanical properties of the defective PtS 2 monolayer under uniaxial tension in the armchair direction have also been studied. The calculations show that the Y s , fracture strain and stress decrease significantly as the rectangular defect enlarging. These results suggest even though the defect itself can induce the mechanical degradation, enlargement of the defect along a direction may promote the mechanical recovery in the same direction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Line defect can tune the mechanical properties of the monolayer PtS 2. • Within the small tilting angle range from 0 ° to 45 ° , the mechanical property is superior in the armchair direction. • In the large tilting angle range from 45 ° to 90 ° , the mechanical property is superior in the zigzag direction. By using the classical molecular dynamics simulations, the mechanical properties of the monolayer (ML) PtS 2 with the line defect of different tilting angles have been investigated. It has been found that mechanical properties including the fracture strain, fracture stress, toughness and Young's modulus in armchair and zigzag directions have been affected in very different levels. With the tilting angle being from 0 ° to 45 ° , the mechanical properties in armchair direction is more superior compared to those in the zigzag direction. On the contrary, the mechanical properties in the zigzag direction are much stronger as tilting angle increasing from 45 ° to 90 °. Tilting angle of 45 ° has been received unrivalled attention, where the ML PtS 2 with the line defect has presented isotropic mechanical properties in armchair and zigzag directions. The systematically parametric study on the line defect has been demonstrated that the tilting angle may change the isotropic property of the ML PtS 2 , resulting from its large length–width ratio and orientation of the line defect to the loading direction. The simulations in this paper shed light on a new possibility of fine-tuning mechanical properties and the realization of the isotropy-to-anisotropy of ML PtS 2 and other two-dimensional materials via line defect, which may expand the potential application these materials in the future nanometer devices. [ABSTRACT FROM AUTHOR]