Electron energy spectrum and peculiarities of optical absorption in single-layer 2D structures based on silicon dioxide with surface functional groups

A calculation scheme based on density functional theory generalized to the case of periodic structures is used to calculate the electron energy spectrum and the imaginary part of the permittivity of single-layer 2D structures based on silicon dioxide with the surface functional groups X ≡ OH, CH3, NH2, NO2, CHO, and COOH. The dependences of the energy corresponding to the energy-band edges, valence-band widths, and the positions of the characteristic peaks of the density of states on the degree of replacement by surface groups The peculiarities of the optical absorption bands in the absorbed photon energy region ħω < 14 eV are revealed.