Effect of polar groups on Raman spectrum of one dimension SiO2 nanowires

Raman vibration spectra of nanoscaled anhydrous and hydrous (SiO2)n (n = 6-20) of single-line, double-line and ring conformations have been calculated using the density functional theory (B3LYP) at 6-31g(d) level. Two specific Raman vibration modes are chosen to demonstrate effect of polar groups. Raman frequency shift law is interpreted successfully using the model of the simple harmonic oscillator combining with the cascade and parallel connection principle. Polarization ratios suggested that polar groups' influence is quite distinct on the different direction due to orientation.