First-principles study of CdSe nanoribbons under uniaxial tensile strain

Abstract

The detailed mechanical, electronic, and magnetic properties, structural transformation, and stability of CdSe nanoribbons (CdSeNRs) under uniaxial tensile strain have been investigated using first-principles calculations. In the elastic range, armchair CdSeNRs (ACdSeNRs) are stretchable up to a strain of 0.18, while zigzag CdSeNRs (ZCdSeNRs) are stretchable up to a strain of 0.16. The band gap decreases as the tensile strain increases in the elastic tensile range, but dramatically increases when the tensile strain exceeds the yielding point for ACdSeNRs because of the shift of the conduction band. Due to the structural transformation from a honeycomb hexagon to a symmetrical square, the magnetic moment of ZCdSeNRs generally changes slightly under elastic tensile strain and decreases as the strain increases in the plastic range. The mechanical properties of nanoribbons are studied by examining the variation of tensile strain energy E_s, which contains information about the nanoribbon's mechanical properties, such as force constant k and in-plane stiffness C. For both ACdSeNRs and ZCdSeNRs, the force constant, k, in relation to the width of the nanoribbons exhibits a nearly linear relationship, with small deviations due to edge effects. The in-plane stiffness C increases marginally with increasing nanoribbon width. The binding energies indicate that armchair nanoribbons are more stable than comparable-width zigzag nanoribbons. Our calculations indicate that the electronic and magnetic properties of CdSeNRs can be modulated effectively by applying tensile strain and that the mechanical properties are highly dependent on the tensile strain and width of the nanoribbons.