AbstractA new calculation of the vibrational frequencies of poly(ethy1 ethylene) based on the actual molecular geometry was performed. The calculation takes into account new experimental data such far‐infrared spectra and Raman spectra of the stretched polymer, infrared spectra of poly(ethyl ethylene)‐(2,2;d2) (P‐4‐1‐d2) and poly(ethyl ethylene)‐(3,3,4,4;d4) (P‐4‐1‐d4), and Raman spectra of poly(ethyl ethylene)‐(1,3,3;d3) and poly(ethyl ethylene)‐(3,3,4,4;d4). Refinement produced a set of force constants; it is also applicable to