Variational design principles for nonequilibrium colloidal assembly

Area of Science:

• Physics
• Chemistry
• Materials Science

Background:

• Molecular dynamics simulations are crucial for understanding self-assembly processes.
• Controlling self-assembly to achieve specific target structures remains a significant challenge.
• Nonequilibrium steady-states offer unique opportunities for manipulating molecular systems.

Purpose of the Study:

• To develop a theoretical framework for inverse design of self-assembly.
• To determine optimal external forces for enhancing the stability of target structures.
• To investigate the role of shear flow in colloidal cluster assembly.

Main Methods:

• Application of large deviation theory and stochastic optimal control.
• Formulation of a variational principle for self-assembly.
• Development of an optimization algorithm for determining external forces.
• Modeling colloidal cluster assembly in linear shear flow.

Main Results:

• Rare molecular trajectories conditioned on target structures encode stabilizing interactions and forces.
• Optimal forces were determined for targeted self-assembly in nonequilibrium steady-states.
• Colloidal clusters were assembled with high yield using tunable short-range interactions.
• Shear flow affects cluster yields: decreasing rigid clusters, increasing nonrigid ones.
• Generalized linear response theory explains shear-induced yield changes.

Conclusions:

• The developed inverse design approach enables precise control over self-assembly.
• Understanding interactions and forces is key to achieving desired structures out of equilibrium.
• Basic design principles for targeted assembly in nonequilibrium systems were uncovered.