Inverse design of interactions for assembly

Nanometer-scale, colloidally-stable particles suspended in a fluid can be driven to assemble into a wide variety of different structures depending on the control parameters of the system and the nature of the effective interparticle interactions. In many cases, the relevant interactions are tunable via external fields, physical or chemical modification of the particle surfaces or changes in the composition of the suspending solvent. In this talk, we discuss some of the theoretical challenges associated with using inverse methods to guide the design of such interactions for assembly of colloidal mesophases with targeted structure [1-3] and the opportunities that new machine-learning based simulation approaches [4,5] may provide for addressing them. [1] R. B. Jadrich, J. A. Bollinger, B. A. Lindquist, and T. M. Truskett, Equilibrium cluster fluids: Pair interactions via inverse design Soft Matter 11, 9342 (2015) [2] B. A. Lindquist, R. B. Jadrich, and T. M. Truskett, Assembly of nothing: Equilibrium fluids with designed structured porosity. Soft Matter 12, 2663 – 2667 (2016) [3] B. A. Lindquist, S. Dutta, R. B. Jadrich, D. J. Milliron, and T. M. Truskett, Interactions and design rules for assembly of porous colloidal mesophases. Soft Matter 13, 1335 (2017) [4] B. A. Lindquist, R. B. Jadrich, and T. M. Truskett, Inverse design for self assembly via on-the-fly optimization. Journal of Chemical Physics 145, 111101 (2016) [5] R. B. Jadrich, B. A. Lindquist, and T. M. Truskett, Probabilistic inverse design for self assembling materials. arXiv:1702.05021 (to appear in Journal of Chemical Physics

Excess-entropy scaling of dynamics for a confined fluid of dumbbell-shaped particles

We use molecular simulation to study the ability of excess entropy scaling relationships to describe the kinetic properties of a confined molecular system. We examine a model for a confined fluid consisting of dumbbell-shaped molecules that interact with atomistically detailed pore walls via a Lennard-Jones potential. We obtain kinetic, thermodynamic, and structural properties of the system at three wall-fluid interaction strengths and over a temperature range that includes sub-and super-critical conditions. Four dynamic properties are considered: translational and rotational diffusivities, a characteristic relaxation time for rotational motion, and a collective relaxation time stemming from analysis of the coherent intermediate scattering function. We carefully consider the reference state used to define the excess entropy of a confined fluid. Three ideal-gas reference states are considered, with the cases differentiated by the extent to which one-body spatial and orientational correlations are accounted for in the reference state. Our results indicate that a version of the excess entropy that includes information related to the one-body correlations in a confined fluid serves as the best scaling variable for dynamic properties. When adopting such a definition for the reference state, to a very good approximation, bulk and confined data for a specified dynamic property at a given temperature collapse onto a common curve when plotted against the excess entropy.National Science Foundation CBET-0828979Welch Foundation F-1696David and Lucile Packard FoundationChemical Engineerin