Density functional calculation of structure and vibrational spectra of polyenes

The vibrational frequencies of a number of all trans polyenes H–(CH=CH)n–H ranging from n=1 to n=12 have been calculated within the density functional approach using a generalized gradient corrected exchange-correlation functional and a gaussian basis set. A remarkably good agreement with available experimental data is obtained. A correlation of the normal frequencies along the polyene series is presented describing the motions according to a nodal analysis. The results obtained are also correlated with the vibrations of an infinite polyenic chain.