This paper is dedicated to Eusebio Juaristi, a friend, teacher and model researcher ( Abstract In this paper we present a theoretical study of the observed IR spectra of some samples of amber. We compare them to theoretically obtained spectra for a model of this natural polymer. The model assumes that communic acid and communol are plausible precursors in the natural polymerization of amber. We employ an electronic structure method at the BP86 density functional theory level. Our electronic

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... cture methodology is found to be appropriate for the study and rationalization of the spectra of the chosen amber samples, with very good agreement with the observed spectra.