Comparing equilibration schemes of high-molecular-weight polymer melts with topological indicators

Area of Science:

• Polymer Physics
• Computational Chemistry
• Materials Science

Background:

• Molecular knots serve as sensitive probes of polymer topology and structure.
• Equilibrating high-molecular-weight (MW) polymer melts is computationally challenging.
• Advanced simulation algorithms are needed to accurately model polymer melts.

Purpose of the Study:

• To validate two state-of-the-art algorithms: configuration assembly and hierarchical backmapping.
• To assess the ability of these algorithms to equilibrate dense, high-MW polymer melts.
• To use molecular knotting properties as a metric for algorithm performance.

Main Methods:

• Generating polymer melts with high molecular weights (tens of entanglement lengths) and varying chain flexibilities.
• Employing both configuration assembly and hierarchical backmapping algorithms.
• Analyzing and comparing knot spectra, unknotting probability, unknotting length, and knot length distributions.

Main Results:

• Excellent agreement was found between the two algorithms regarding polymer knotting properties.
• Both configuration assembly and hierarchical backmapping successfully equilibrated the simulated polymer melts.
• Knotting behavior provided a consistent and reliable validation metric for the algorithms.

Conclusions:

• Configuration assembly and hierarchical backmapping are validated for equilibrating high-MW polymer melts.
• Molecular knotting analysis offers a robust method for verifying polymer melt simulations.
• This work enables the study of polymer topological properties at unprecedented scales.