Normal Modes of Poly(L-valine) in Relation to Spectra of Oligovalines

Poly(L-valine) (PLV) belongs to the class of polyamino acids having a bulky side chain. It preferably adopts beta-sheet conformation, although high molecular weight PLV may form an alpha helix as well. In the present communication we report a detailed study of the phonons and their dispersion for beta-PLV and the spectra of oligovalines in relation to its polymeric form. The N-deuterated analog of beta-PLV has also been studied to confirm the correctness of assignments and force-field. Density-of-states and heat capacity have been obtained. The heat capacity is in very good agreement with the experimental measurements of Roles et al.