Earlier works on polyglycine I suffer from several infirmities, such as the dynamic methylene group being replaced by a mass unit and the use of poorly resolved inelastic neutron spectra, which have resulted in wrong assignments and imprecise profile of dispersion curves. In addition, the density-of-states and heat capacity variation as a function of temperature are being reported for the first time. The heat capacity is in good agreement with the measurements reported earlier by Roles and

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... rlich within a certain range (230-350 K). Deviations set in beyond this could be due to the presence of two crystalline states (I and II) in the sample used for the heat capacity measurements.