A MOLECULAR-DYNAMICS METHOD FOR OBTAINING THE VIBRATIONAL-SPECTRA OF MACROMOLECULES

A molecular dynamics-based method is used to compute the vibrational s pectra and dispersion curves of a polyethylene chain. The results are compared and contrasted with those of normal mode calculations, demons trating the validity of the approach and providing fundamental insight into a number of dynamical processes. The strength of the method is i ts computational efficiency and that it represents an exact classical dynamics approach to calculating vibrational spectra, thereby eliminat ing many of the weaknesses of normal mode calculations (i.e., the harm onic approximation).