Effective potentials for representing polymers in melts as chains of interacting soft particles

Area of Science:

• Polymer Physics
• Computational Chemistry
• Materials Science

Background:

• Coarse-graining simplifies complex polymer systems by representing groups of monomers as single particles.
• Understanding inter-particle interactions is key to predicting polymer melt behavior.
• Existing models often require accurate potential functions for structural and thermodynamic properties.

Purpose of the Study:

• To derive an analytical pair potential for a coarse-grained polymer melt model.
• To investigate the relationship between potential features and system properties.
• To assess strategies for determining accurate potentials in coarse-grained simulations.

Main Methods:

• Developing an analytical pair potential for soft spheres representing polymer subchains.
• Analyzing the short-range repulsive and long-range attractive components of the potential.
• Comparing the influence of potential features on liquid structure and thermodynamics.

Main Results:

• The derived potential features a soft repulsive core and a long-range tail with a small attractive component.
• Short-range potential features primarily influence liquid structure.
• Long-tail features significantly impact virial-route thermodynamics.

Conclusions:

• Accurate determination of both short- and long-range features of the effective potential is essential for coarse-grained polymer melts.
• Optimizing potentials solely based on structural data is unreliable for thermodynamic accuracy in dense systems.
• The level of coarse-graining impacts the form and relevance of potential components.