First-principle simulations of electronic structure in semicrystalline polyethylene

Area of Science:

• Materials Science
• Computational Chemistry
• Solid State Physics

Background:

• High-voltage cable insulation relies on polyethylene (PE) properties.
• Understanding PE's electronic structure is crucial for material development.
• Existing models require refinement for realistic PE structures.

Purpose of the Study:

• To investigate the electronic structure of realistic polyethylene models.
• To analyze charge carrier localization and transport in various PE structures.
• To provide fundamental insights into PE as a high-voltage insulator.

Main Methods:

• Novel molecular modeling strategy combining Monte Carlo and molecular dynamics.
• First-principles electronic structure simulations using linear-scaling density functional theory (LS-DFT).
• Validation of LS-DFT with conventional DFT and comparison with experimental data.

Main Results:

• Modeled PE structures agree with experimental data.
• Localized electronic states identified in amorphous regions, branches, and crosslinks.
• Simulated bandgaps align with experimental values using hybrid functionals.
• Low effective activation energy for charge transport at room temperature.

Conclusions:

• Polyethylene's electronic structure is sensitive to its morphology (amorphous, crystalline, branched, crosslinked).
• Charge carriers exhibit high mobility due to localized states and low activation energy.
• These findings support the use of PE in high-voltage cable insulation and suggest potential for hot carrier transport.