The semiclassical spectral method (SSM), which employs molecular dynam
ics and spectral estimators to determine transition frequencies betwee
n quantum energy levels in molecular and atomic systems, is extended t
o include calculations for linear polymer chains. Average differences
between harmonic and transition frequencies for the symmetric and asym
metric stretch modes of polyethylene are reported to be around 50 cm-1
with smaller average frequency shifts for the other group vibration d
ispersion curves for a certain potential surface describing the macrom
olecule.