Structural and electronic properties of Penta-P2X (X=C, Si and Ge) nanoribbon under mechanical strain: density functional theory

Using the density functional calculations, the band structure and electronic properties of pentagonal P2X (X=C, Si and Ge) nanoribbons with various edges subjected to uniaxial tensile and compressive strains were investigated. In their unstrainedstate, all nanoribbon structures exhibit an indirect band gap ranging from 1.87 to 2.02 eV, a characteristic that can be modulatedthrough external strain. Our findings demonstrate that, under tensile strain P2C nanoribbons with all three different edges undergo a transition from an indirect to a direct band gap, accompanied by a reduction in the band gap value. Additionally, we investigated charge transfer between atoms in the nanoribbons using Bader charge density calculations. The findings revealed that there is a correlation between the electronegativity of atoms and the amount of Bader charge. Analyzing the partial density of states for the nanoribbons reveals that central atoms play a significant role in energy levels near the Fermi level. The edge atoms in the nanoribbons have formed strong sigma bonds with hydrogen atoms. Their energy levels are more stable than the central states, and for this reason, the contribution of the orbitals related to the edge atoms is located further from the Fermi energy, and the edge of the Fermi energy belongs to the central atoms.