Computational density functional theory vibrational spectra of cubane

The performance of various Density Functional Theory (DFT) functionals and additional frequency scaling for predicting cubane vibrational harmonic frequencies is evaluated. All studied DFT functionals give more accurate frequencies (i.e., in better agreement with experimental values) not only than Hartree-Fock calculations (as expected) but also better than performed localized MP2 (LMP2) calculations. This accuracy can be additionally enhanced by frequency scaling. The B3LYP, B3PW91 and SVWN functionals are best suited for evaluation of vibrational frequencies of cubane. However, SVWN functional performs more poorly than other DFT functionals in reproducing cubane geometry.