Time Autocorrelation Function of Intramolecular Dipole Moments for Type-A Polymer Glass

We compute the high-frequency spectra of the intermolecular dipole moment correlation for a model polymer near the glass transition by molecular dynamics simulation without charge distribution. The dielectric properties are calculated by introducing the inherent dipoles which are virtually placed along the chains as forming the type-A polymer. The high-frequency loss peak corresponding to the local motions of molecules is observed at around 10 THz. The spectra are strongly deviated from a Lorentian distribution, which causes a large so-called tangential delta near the peak frequency as well.