Angle-resolved effective potentials for disk-shaped molecules

Area of Science:

• Computational chemistry
• Materials science
• Statistical mechanics

Background:

• Accurate molecular simulations require effective potentials that balance computational cost and physical realism.
• Coarse-grained models simplify complex molecular systems but often struggle to capture anisotropic interactions.
• Uniaxial molecules, like disk-like coronene, present unique challenges for traditional simulation methods.

Purpose of the Study:

• To develop a method for calculating angle-resolved effective pair potentials for coarse-grained simulations of uniaxial molecules.
• To investigate the temperature and angle dependence of these coarse-grained potentials.
• To evaluate the accuracy of these potentials in reproducing structural and thermodynamic properties compared to atomistic simulations.

Main Methods:

• Atomistically-resolved molecular dynamics (MD) simulations using umbrella sampling and steered dynamics.
• Integration of van der Waals and intramolecular interactions, neglecting electrostatic contributions.
• Fitting numerical data to Gay-Berne-like potentials for efficient large-scale simulations.

Main Results:

• The derived coarse-grained pair potential exhibits significant temperature and angle dependence.
• Angle-resolved potentials are essential for accurately describing both crystal and fluid structures.
• Simple isotropic potentials fail for fluid systems at low to moderate packing fractions.

Conclusions:

• Coarse-grained angle-resolved potentials are vital for accurate molecular simulations, especially for anisotropic molecules.
• The temperature dependence of pair potentials, influenced by bending fluctuations, is critical for describing fluid states.
• This approach enables more efficient and accurate large-scale simulations of complex molecular systems.