Optical response of liquid acetonitrile at ambient conditions: the dynamical dielectric behavior from ab initio calculations.

We probe the linear optical properties of the neat liquid acetonitrile (CH(3)CN) at ambient conditions using ab initio density functional theory. Uncorrelated structures extracted from Monte Carlo simulation are employed to efficiently calculate average electronic properties. It becomes evident that condensation leads to a conduction band with a large degree of dispersion, which is consistent with the description of dipolar liquids. This allows an interpretation of the dielectric spectrum based on the electronic structure of liquid CH(3)CN, and clearly shows the influence of intermolecular interactions in the absorption features. We find that the lowest-lying excitation of the condensed phase occurs at 7.8 eV, which is reasonable as compared to the 8-9.5 eV absorption region measured in the gas phase.

Effects of hydroxyl group distribution on the reactivity, stability and optical properties of fullerenols.

We investigate the impact of hydroxyl groups on the properties of C(60)(OH)(n) systems, with n = 1, 2, 3, 4, 8, 10, 16, 18, 24, 32 and 36 by means of first-principles density functional theory calculations. A detailed analysis from the local density of states has shown that adsorbed OH groups can induce dangling bonds in specific carbon atoms around the adsorption site. This increases the tendency to form polyhydroxylated fullerenes (fullerenols). The structural stability is analyzed in terms of the calculated formation enthalpy of each species. Also, a careful examination of the electron density of states for different fullerenols shows the possibility of synthesizing single molecules with tunable optical properties.