Theoretical calculations of the structure and UV-vis absorption spectra of hydrated C_(60) fullerene

摘要

A combined Monte Carlo simulation with semiempirical quantum mechanics calculations has been performed to investigate the structure of hydrated fullerene (CeoHyFn) and the influence of hydration on its UV-vis spectra. The statistical information of the C_(60) fullerene aqueous solution (C_(60)FAS) is obtained from NPT ensemble including one C_(60) fullerene immerses in 898 water molecules. To obtain an efficient ensemble average, the auto-correlation function of the energy has been calculated. The analyzed center-of-mass pair-wise radial distribution function indicates that, on average, there are 65 and 151 water molecules around the first and second hydration shells, respectively, of a single C_(60) molecule. To calculate the average UV-vis transition energies of C_(60)HyFn, only the statistically uncorrelated configurations are used in the quantum mechanical calculations (INDO/CIS). These involve hundreds of supramolecular structures containing one C_(60) fullerene surrounded by the first hydration shell. The calculated average transitions at 268 and 350 nm are in very good agreement with the experimental prediction.