Density Functional Theory Study of Vibrational Spectra. 3. Assignment of Fundamental Vibrational Modes of Quadricyclane

Density functional theory BLYP (Becke\u27s exchange and Lee-Yang-Parr\u27s correlation functionals), ab initio Hartree-Fock (HF) and hybrid DFT/HF B3LYP calculations were carried out to study the structure and vibrational spectra of quadricyclane. The BLYP/6-31G* and scaled HF/6-31G* frequencies correspond well with each other and with available experimental assignment of the fundamental vibrational modes. Based on conformity between the calculated and experimental results, a plausible assignment of two remaining a1 modes and all non-CH stretching a2, b1, and b2 modes is proposed