DENSITY-FUNCTIONAL THEORY STUDY OF VIBRATIONAL-SPECTRA OF FLUORENE

Ab initio Hartree-Fock and density functional theory calculations usin g the 6-31G basis set were carried out to study the molecular structu re and vibrational spectrum of fluorene (FR). Two density functionals were employed: the (1) Becke-Lee-Yang-Parr (BLYP) functional and (2) t he Becke 3-Lee-Yang-Parr (B3LYP) functional. Comparison of the calcula ted and experimental vibrational spectra reveals that the B3LYP calcul ations are quite accurate in predicting the vibrational frequencies an d modes. We report the results of new assignments of the fundamental v ibrational frequencies obtained on the basis of the calculations. The new assignments show a one-to-one correspondence between the observed and calculated fundamentals.