Formulation of improved basis sets for the study of polymer dynamics through diffusion theory methods

Area of Science:

• Polymer Physics
• Computational Chemistry
• Theoretical Chemistry

Background:

• Diffusion theory (DT) is a powerful tool for simulating polymer dynamics.
• Traditional DT methods rely on specific basis function selection techniques like long time sorting procedure (LTSP) and maximum correlation approximation (MCA).
• Limitations exist in the efficiency and numerical stability of existing basis function selection methods.

Purpose of the Study:

• To introduce a novel hybrid basis approach (HBA) for selecting basis functions in diffusion theory calculations.
• To enhance the efficiency, convergence, and numerical stability of DT simulations.
• To validate the HBA method by comparing its results with molecular dynamics (MD) simulations and experimental data.

Main Methods:

• The hybrid basis approach (HBA) combines LTSP and MCA techniques.
• HBA employs a first-order basis set equivalent to a high-order MCA set and generates higher-order approximations using LTSP.
• DT calculations with HBA were performed on polymer melts and solutions, with validation against MD simulations and experimental parameters.

Main Results:

• HBA demonstrated improved convergence properties and numerical stability compared to LTSP for cis-1,4-polyisoprene decamers.
• DT calculations using HBA for syndiotactic trans-1,2-polypentadiene in toluene showed excellent agreement with MD simulations.
• The study successfully reproduced polymer dynamical properties using equilibrium averages from vacuum trajectories and experimental data.

Conclusions:

• The hybrid basis approach (HBA) offers a significant advancement in diffusion theory calculations for polymer dynamics.
• HBA provides a computationally efficient and accurate method for bridging theoretical predictions with experimental static and dynamic polymer properties.
• This approach enables reliable simulations using minimal experimental inputs like mean radius of gyration and solution viscosity.