PNNL

Abstract

Time-dependent density functional theory (TD-DFT) calculations of the transition energies and oscillator strengths of fluorinated methanes have been performed. The TD-DFT method with the nonlocal B3LYP potential yields transition energies which are smaller by about 10% as compared to the experimental values for these molecules. An empirical linear correlation was found between the calculated and experimental transition energies both at the B3LYP/DZ+ and B3LYP/cc-pVTZ+(+H) levels for a total of 19 transitions of the fluorinated methanes with linear correlation coefficients of 0.987 for the former and a 0.988 for the latter. This empirical correlation for fluorinated methane molecules is found to agree well with the previously obtained empirical correlations between calculated and experimental values for non-fluorinated molecules. The results show that a single empirical correlation equation can be used for both non-fluorinated and fluorinated molecules to predict transition energies.