The electronic and optical properties of N atom‐width (N: 4, 8, 12, 16) armchair GaAs nanoribbons (NA GaAs NRs) have been studied with hydrogen (H) passivated nanoribbons using the DFT approach. The H passivated edge of NA GaAs NRs with different widths of nanoribbons provide great flexibility to modulate the fundamental band gap. All investigated width of 4, 8, 12, and 16 atom GaAs NRs are found to be semiconducting with direct band gaps of 3.071, 2.275, 2.155, and 2.02 eV respectively at k‐point Z (0, 0, 0.5), which exhibit interesting width dependent (N: 4~12) behaviour of the band gap. The complex dielectric constant was calculated using the Kubo‐Greenwood formula, from which the refractive index(n(ω)) and absorption coefficient () were also calculated for the bulk as well as for all width of GaAs armchair nanoribbons. The nzz and components significantly play a major role in tuning the refractive index and optical absorption coefficient of the GaAs nanoribbons.
