A multi-species exchange model for fully fluctuating polymer field theory simulations

Area of Science:

• Computational physics and chemistry
• Polymer science and engineering
• Soft matter physics

Background:

• Field-theoretic models are crucial for understanding polymer phase behavior in inhomogeneous systems.
• Existing models include species and exchange types, with exchange models enabling stable complex Langevin (CL) simulations for two-component systems.
• Stable CL simulations for species-type field theories remain a challenge.

Purpose of the Study:

• To introduce a generalized exchange model for an arbitrary number of components.
• To enable complex Langevin simulations for a wider range of soft material systems.
• To demonstrate the stability and accuracy of the new simulation approach.

Main Methods:

• Development of the multi-species exchange (MSE) model, extending the exchange model framework.
• Implementation of the MSE model within the complex Langevin (CL) simulation technique.
• Numerical simulations of triblock terpolymer melts, tetrablock terpolymer melts, and tetrablock quaterpolymer melts.

Main Results:

• The multi-species exchange (MSE) model successfully extends the capabilities of complex Langevin (CL) simulations to systems with multiple components.
• Numerical simulations demonstrated the stability and accuracy of the MSE-CL sampling approach for various multiblock polymer melts.
• The new method significantly expands the range of accessible soft material systems for computational study.

Conclusions:

• The MSE model provides a robust framework for simulating complex polymer systems.
• This approach facilitates the study of fluctuation phenomena in multiblock and multi-species polymer blends and composites.
• The MSE-CL technique opens new avenues for theoretical and computational research in soft matter.