Theoretical modeling of the peroxide stretch in H₂O₂, F₂O₂, and Fe₂O₄

The structures and harmonic vibrational spectra of H 2 O 2 , F 2 O 2 , Fe 2 O 4 , and Fe 2 O 4 (H 2 O) 6 have been examined in theoretical electronic structure calculations. A variety of density functionals and basis sets have been employed to sample the consistency to be expected in calculations on peroxodiiron (III) complexes. It is found that both Gaussian function and numerical basis sets are capable of satisfactory accuracy in determining geometries and vibrational frequencies. Several density functionals fit the experimental vibrational spectra of H 2 O 2 and F 2 O 2 adequately; the BPW91 functional provides the best overall fit.