Coarse-grained models for local density gradients

Area of Science:

• Computational materials science
• Soft matter physics
• Chemical engineering

Background:

• Coarse-grained (CG) models enhance simulation efficiency for soft materials.
• Conventional CG models with pair-additive potentials lack transferability between bulk and interfacial regions.
• One-body potentials of local density (LD) improve CG model accuracy but struggle with rapidly changing interfacial LD.

Purpose of the Study:

• Introduce and investigate a new class of one-body potentials dependent on the square of the local density gradient (SG potentials).
• Evaluate the impact of SG potentials on both top-down dissipative particle dynamics (DPD) and bottom-up multiscale coarse-graining (MS-CG) models.
• Assess the ability of SG potentials to improve the description of interfacial properties and bulk behavior in CG simulations.

Main Methods:

• Developed and implemented square gradient (SG) potentials for CG simulations.
• Applied SG potentials to dissipative particle dynamics (DPD) models.
• Integrated SG potentials into multiscale coarse-graining (MS-CG) models for acetic acid simulations.

Main Results:

• SG potentials effectively tune interfacial properties in DPD models without significantly altering bulk characteristics.
• SG potentials improved the bulk pressure-density equation of state for MS-CG models.
• SG potentials enhanced the interfacial profile accuracy in MS-CG models for acetic acid.

Conclusions:

• SG potentials offer a promising method for improving the accuracy and transferability of CG models, especially for interfaces.
• SG potentials may bridge particle-based models and continuum theories like Landau theories for phase behavior.
• The developed SG potentials are valuable for simulating inhomogeneous systems with significant density gradients.