Electron trapping in polyethylene

We use the pseudopotentials describing the excess electron-polyethylene interaction to study the relation between electron trapping with a series of geometries which are representative of different morphologies found in pure polyethylene (PE). We first use an united atom model to generate these geometries, which include crystalline, lamellae, and amorphous regions, in addition to two interfaces between lamellae and amorphous regions corresponding to two different orientations (interfacial-parallel and interfacial-perpendicular). Then we use a fast Fourier transform block Lanczos diagonalization algorithm to study the electronic states of excess electrons in these molecular models of different morphologies of polyethylene. We find that, regardless of the specific geometry, the excess electron is more likely to sit in the low density regions, with a clear negative correlation between the atomic density and the ground state electron probability density. For the interfaces, the lowest energies of the excess electron are located near the interfacial area between the lamellae and amorphous regions, which indicates that the interfaces may actually play an important role in the electronic properties of PE. In addition, we also estimate the mobility edges separating localized from delocalized states in these geometries, offering a clear image of electronic transport through the extended states in the representative regions of PE.