The behavior of active diffusiophoretic suspensions: An accelerated Laplacian dynamics study

Abstract

This article presents a perspective on Kohn-Sham density functional theory (KS-DFT) for electronic structure calculations in chemical physics. This theory is in widespread use for applications to both molecules and solids. We pay special attention to several aspects where there are both concerns and progress toward solutions. These include: 1. The treatment of open-shell and inherently multiconfigurational systems (the latter are often called multireference systems and are variously classified as having strong correlation, near-degeneracy correlation, or high static correlation; KS-DFT must treat these systems with broken-symmetry determinants). 2. The treatment of noncovalent interactions. 3. The choice between developing new functionals by parametrization, by theoretical constraints, or by a combination. 4. The ingredients of the exchange-correlation functionals used by KS-DFT, including spin densities, the magnitudes of their gradients, spin-specific kinetic energy densities, nonlocal exchange (Hartree-Fock exchange), nonlocal correlation, and subshell-dependent corrections (DFT+U). 5. The quest for a universal functional, where we summarize some of the success of the latest Minnesota functionals, namely MN15-L and MN15, which were obtained by optimization against diverse databases. 6. Time-dependent density functional theory, which is an extension of DFT to treat time-dependent problems and excited states. The review is a snapshot of a rapidly moving field, and-like Marcel Duchamp-we hope to convey progress in a stimulating way. Published by AIP Publishing. [http://dx

Hydrochemical interactions of phoretic particles: a regularized multipole framework

“…its first two moments over the particle's surface. Using the multipole expansion of the fundamental integral representation of the concentration (see Appendix A), the monopole and dipole intensities of particle n, q M n and q D n , are obtained as (Yan & Brady 2016)…”

“…Due to the mathematical similarities between the Laplace and Stokes problems, it is possible to draw inspiration from and build upon a large variety of methods already used in recent years for the numerical modelling of passive and active suspensions. A popular example is the Stokesian dynamics and its more recent extensions (Brady & Bossis 1988; Sierou & Brady 2001; Swan, Brady & Moore 2011; Fiore & Swan 2019), from which an analogous approach was proposed to solve for diffusion problems (Yan & Brady 2016). A similar approach relies on a truncated spectral expansion of the integral formulation of the Laplace and Stokes equations with tensorial spherical harmonics on the particle's surface (Singh & Adhikari 2019; Singh, Adhikari & Cates 2019).…”

Faxén formulas for particles of arbitrary shape and material composition

“…(2013). Furthermore, our results could be used to incorporating hydrodynamic interactions into the Laplacian dynamics (Bonnecaze & Brady 1990; Yan & Brady 2016) framework. One could imagine using (3.23) and similar equations derived for other boundary conditions to serve as a theoretical basis for extending dynamic simulations to systems involving couplings between momentum and mass, charge or heat transport.…”

Active colloids with collective mobility status and research opportunities

“…2 Recently, Brady and coworkers worked out a manyparticle solute concentration field that allows dynamic simulation of the motion of many reactive Janus particles, and demonstrated exponentially screened long-ranged interactions. 78 The selfpropulsion of such chemically communicating particles contributes to collective behavior by allowing coexistence of dilute and dense regions, whereas uniformly reactive particles would only form loosely packed clusters without the coexistence of differential density regions. 78 Hydrodynamic communication.…”

“…78 The selfpropulsion of such chemically communicating particles contributes to collective behavior by allowing coexistence of dilute and dense regions, whereas uniformly reactive particles would only form loosely packed clusters without the coexistence of differential density regions. 78 Hydrodynamic communication. As hydrodynamic interactions are always present between particles suspended in a fluid, they compete with other interactions.…”