Validating Structural Predictions of Conjugated Macromolecules in Espaloma-Enabled Reproducible Workflows.

Area of Science:

• Computational chemistry
• Materials science
• Organic electronics

Background:

• Molecular dynamics (MD) simulations are crucial for predicting material properties.
• Accurate force fields are essential for reliable MD simulations of organic molecules.
• Espaloma offers a novel approach to force field parameterization.

Purpose of the Study:

• To integrate Espaloma force field parameterization into MoSDeF tools for MD simulations.
• To compare the predictive capabilities of ESP-UA and OPLS-UA force fields for organic molecules.
• To evaluate the performance of ESP-UA in capturing experimentally observed morphologies and phase behaviors.

Main Methods:

• Incorporation of Espaloma force field parameterization into MoSDeF.
• Performing molecular dynamics simulations of perylene and poly-3-hexylthiophene (P3HT) using HOOMD-Blue.
• Comparison of equilibrium morphologies, phase behavior, and ordering using radial distribution functions and grazing incidence X-ray scattering.

Main Results:

• ESP-UA, after resolving topological ambiguities, demonstrates similarity to GAFF.
• Clustering/melting phase behavior is comparable between ESP-UA and OPLS-UA.
• ESP-UA shows improved matching with experimental long-range ordering compared to OPLS-UA, while short-range ordering is identical.
• OPLS-UA's base energy unit better correlates with experimental transition temperatures.

Conclusions:

• Espaloma shows potential for automated screening of molecules within complex chemical spaces.
• The ESP-UA force field provides a valuable alternative for simulating organic materials.
• Further development of Espaloma could enhance the prediction accuracy of molecular morphologies and properties.