Vibrational Dynamics of Poly(l-asparagine)

The normal modes and their dispersions for poly(l-asparagine) (PLN) in the α-helical form have been obtained in a reduced zone scheme with Wilson's GF matrix method as modified by Higgs. The results indicate that the modes below 1350 cm^?1 show appreciable dispersion. Optically active frequencies corresponding to the zone center and zone boundary are identified and discussed. Some of the characteristic features of the dispersion curves are repulsion accompanied by an exchange of character and von Hove singularities. Amide modes, side chain modes, and mixed modes are reported. The heat capacity calculated from the dispersion curves via density-of-states using Debye's relation is compared with the experimental data in the temperature range of 220–390 K.