ALGEBRAIC DESCRIPTION OF N-ALKANE MOLECULES

We apply in a systematic fashion the vibron model to obtain the complete description of vibrational spectra of molecular chains of finite size, such as n-alkanes (paraffin molecules). The one-dimensional model is extended to include infrared spectra of both CH stretching and bending modes. We describe the possible effect of anharmonic (Fermi) resonances in the spectra of fundamental and overtone energy regions. In the present framework, we show that in such molecular systems the algebraic treatment leads to a reliable, consistent set of parameters providing a fair description of the infrared spectrum without including Fermi resonances, even if they can have an appreciable role at higher resolution. It also seems that the parameters are applicable to extend the computation to longer and longer chains eventually describing a polymer chain (polyethylene).