Delving into the design of low – dimensional scandium nitride single and – multilayers, and single and – multiwalled zigzag nanotubes

Abstract

Herein, we exploit quantum-mechanical simulations based on the density functional theory (DFT) to the study of lattice dynamics and structural stability of scandium nitride ScN from the 3D bulk, the square 2D mono and multi-layers to the corresponding single and multi-walled zigzag nanotubes. An effective variety of energetic and geometric parameters as well as electronic and vibrational contributions to the polarizability are established. For all forms, dynamic stability is analyzed via vibrational studies through the simulation of their IR and Raman spectra by using a coupled perturbed Kohn-Sham and Hartree-Fock (CPKS/HF) computational approach. The mechanical response is further achieved by computing their elastic constants that satisfy the mechanical stability criterion. Upon building the 2D square multilayers, a noticeable IR and Raman active modes are generated with the interlayer distance that breaks inversion symmetry and alters the lattice dynamics. By increasing the number of layers, E_u modes become softer and shift toward lower wavelengths while A_2u modes harden with a red shift owing to mechanical deformations that occur between layers. The vibrational active modes of (n,0) ScN square single walled nanotubes are found to be connected with those of the square monolayer as the 1D → 2D transition is approached. The dynamical and structural stability of all forms suggest interesting possibilities for engineering the physical properties of scandium nitride and impact the fabrication of new potential optoelectronic devices.