Fluids density functional theory and initializing molecular dynamics simulations of block copolymers.

Area of Science:

• Polymer physics
• Soft matter theory
• Computational materials science

Background:

• Classical fluids density functional theory (fDFT) predicts equilibrium density profiles for polymeric systems.
• Coarse-grained molecular dynamics (MD) simulations reveal structure and dynamics in soft materials.
• Both fDFT and MD utilize similar bead-based polymer models.

Purpose of the Study:

• To employ fDFT and MD in tandem for a comprehensive study of polymeric systems.
• To leverage the distinct strengths of fDFT and MD methodologies.
• To accelerate MD simulations by using fDFT-derived density profiles for initialization.

Main Methods:

• Implementation of bead-based polymer models compatible with both fDFT and MD.
• Application of fDFT to predict equilibrium density profiles.
• Execution of coarse-grained MD simulations.
• Initialization of MD simulations using fDFT results to achieve near-equilibrium structures.
• Constant pressure simulations for both fDFT and MD.

Main Results:

• Successful application of the tandem fDFT-MD approach to study microphase separated states in diblock and tapered diblock copolymers.
• Both methods consistently predict a decrease in total density with increased segregation strength or tapered region length.
• fDFT and MD predictions for density profiles show strong agreement across a range of interfacial widths.

Conclusions:

• The combined fDFT-MD approach offers a powerful and accurate method for investigating the structure and phase behavior of polymeric materials.
• fDFT-initialized MD simulations can significantly enhance computational efficiency.
• The study validates the predictive capabilities of both theoretical frameworks for copolymer systems.