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Simultaneous calculations of both frequencies and intensities in vibrational spectra, outside of purely theoretical (quantum mechanical) approaches, have been hampered by difficulties in determining transferable intensity parameters from available experimental data. Objectively, intensity parameters are expected to be less transferable compared to force constants because of the higher sensitivity of band intensities to structural changes. There are, however, a number of series of molecules where intramolecular forces and charge distribution are fairly constant, and therefore transferability of both frequency and intensity parameters is expected. A good example in this respect is the normal paraffins. In this paper we present results on the computation of the infrared spectral curves in $C4,C5$ and $C6$ n-alkanes, based on transferable force constants proposed by Shimanouchi $etal.1$, and local C-H and C-C intensity parameters determined from experimental gas phase infrared intensities of ethane and $propane.2$ The presence of different conformational forms is also considered.