Structure, stability, depolarized light scattering, and vibrational spectra of fullerenols from all-electron density-functional-theory calculations

Abstract

We have investigated the stability, electronic properties, Rayleigh (elastic), and Raman (inelastic) depolarization ratios, infrared and Raman absorption vibrational spectra of fullerenols $[{\mathrm{C}}_{60}{(\mathrm{O}\mathrm{H})}_{n}]$ with different degrees of hydroxylation by using all-electron density-functional-theory (DFT) methods. Stable arrangements of these molecules were found by means of full geometry optimizations using Becke's three-parameter exchange functional with the Lee, Yang, and Parr correlation functional. This DFT level has been combined with the $6\text{\ensuremath{-}}31\mathrm{G}(d,p)$ Gaussian-type basis set, as a compromise between accuracy and capability to treat highly hydroxylated fullerenes, e.g., ${\mathrm{C}}_{60}{(\mathrm{O}\mathrm{H})}_{36}$. Thus, the molecular properties of fullerenols were systematically analyzed for structures with $n=1$, 2, 3, 4, 8, 10, 16, 18, 24, 32, and 36. From the electronic structure analysis of these molecules, we have evidenced an important effect related to the weak chemical reactivity of a possible ${\mathrm{C}}_{60}{(\mathrm{O}\mathrm{H})}_{24}$ isomer. To investigate Raman scattering and the vibrational spectra of the different fullerenols, frequency calculations are carried out within the harmonic approximation. In this case a systematic study is only performed for $n=1\char21{}4$, 8, 10, 16, 18, and 24. Our results give good agreements with the expected changes in the spectral absorptions due to the hydroxylation of fullerenes.