The polar tensors, atomic effective charges, and infrared vibrational intensities of C6H6, C6D6, and C6F6

The preferred experimental set of signs for the ∂p/∂Qi’s of C6H6 and C6D6 have been determined from the gas phase infrared intensities of these molecules. This set for C6H6 is in agreement with the one found previously for this molecule based on data for C6H6, C6H5D, and p-C6H4D2. Polar tensors, atomic mean dipole moment derivatives, anisotropies, and effective charges for C6H6, C6D6, and C6F6 are reported. The isotopic invariance of these quantities as indicators of the correct sign choice for the ∂p/∂Qi’s is investigated for C6H6 and C6D6. Several applications of the G-sum rule are made: (a) its usefulness in pointing out the correct signs of the ∂p/∂Qi is investigated, (b) corrected values for the intensity sums of C6H5D and p-C6H4D2 are calculated, and (c) intensity sums for C6H4F2 and C6H2F4 are predicted.