Normal modes and their dispersion in a form of nylon-6 (alpha NY6)

Nylon-6 [-(CH2)5–NHCO-]n ( NY6) is a synthetic polymer widely used in industrial applications. It has a planar zigzag conformation. A comprehensive study of the normal modes and their dispersion in NY6 using Urey Bradley force field is being reported. Crossing between the various pairs of modes of dispersion curves have been explained as arising due to internal symmetry in the energy momentum space. The heat capacity derived from the dispersion curves via the density-of-states, is in good agreement with the experimental measurements obtained from the Athas data bank. [doi:10.1295/polymj.PJ2006103]