Tuning the optical properties of (TiO2)2 via the electric field

TiO2 nanomaterials have extreme applications in photocatalysis and photocell. The study of the properties of TiO2 clusters can provide meaningful references for further understanding of TiO2 nanomaterials. In this paper, tuning the optical properties of (TiO2)(2) cluster was realized by applying an external electric field. The effect of the electric field on the IR spectra, energy gap, linear optical coefficient alpha and the second-order nonlinear optical coefficient beta of (TiO2)(2) cluster were concluded by density functional theory(DFT) method at B3LYP/6-311+G(d, p) basis set. The frequency shift and appearance of a new peak will happen in IR spectra with the fields. UV-vis absorption spectra were investigated using time-dependent density functional theory(TD-DFT) method. The absorption peak of the UV-vis absorption spectra redshift with the electric field increasing and a new absorption peak occurs in visible light range. Besides, the energy gap of (TiO2)(2) cluster begins to decrease with the increase of the field. And the linear optical coefficient alpha and the second-order nonlinear optical coefficient beta are found to increase. Especially, beta rises particularly fast.