Silicon doping on nanotubular fullerene D5h–C90 from first principles

Abstract

This work presented theoretical studies of nanotubular fullerene C90 upon the silicon substitutional doping by means of density functional theory combined with self-consistent field molecular orbital method. The doping effect on geometrical structure, relative stability, defect formation energy, electronic property, nonlinear optical property and aromaticity of the tube-shaped C90 fullerene has been addressed systemically and in details with B3LYP method. It is observed that the silicon atoms exhibit extroversion trend in the doped structure. The obtained defect formation energy is in the range of 4.861–5.231eV for the doped C90 studied, and the substitutionally doping the C90 by Si atom is more favorable to occur near the cap region according to the calculated defect formation energies. The distributions for the highest occupied molecular orbital of the doped C90 are approach to that of the pure C90 fullerene. However, the lowest unoccupied orbital of most doped C90 exhibit obvious localization at the silicon site. To study the nonlinear optical property of the doped structures, the third-order nonlinear optical constant, γ is computed with finite-field method. The enhanced values of nonlinear optical constant of the fullerenes upon silicon doping are observed and understand by γ density analysis. Moreover, the doping effect on the aromaticity of the nanotubular is also studied based on the probe of nuclear independent chemical shift.