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Dynamical density functional theory (DDFT) is a powerful variational framework to study the nonequilibrium properties of colloids by only considering a time-dependent one-body number density. Despite the large number of recent successes, properly modeling the long-time dynamics in interacting systems within DDFT remains a notoriously difficult problem, since structural information, accounting for temporary or permanent particle cages, gets lost. Here we address such a caging scenario by reducing it to a clean one-dimensional problem, where the particles are naturally ordered (arranged on a line) by perfect cages created by their two next neighbors. In particular, we construct a DDFT approximation based on an equilibrium system with an asymmetric pair potential, such that the corresponding one-body densities still carry the footprint of particle order. Applied to a system of confined hard rods, this order-preserving dynamics (OPD) yields exact results at the system boundaries, in addition to the imprinted correct long-time behavior of density profiles representing individual particles. In an open system, our approach correctly reproduces the reduced long-time diffusion coefficient and subdiffusion, characteristic for a single-file setup. These observations cannot be made using current forms of DDFT without particle order., Comment: A limited number of open eprints of the original article is available at https://www.tandfonline.com/eprint/MNBYTHZKYBH3QQH5T5PA/full?target=10.1080/00268976.2020.1867250

Starting from the many-particle Smoluchowski equation, we derive dynamical density functional theory for Brownian particles with an arbitrary shape. Both passive and active (self-propelled) particles are considered. The resulting theory constitutes a microscopic framework to explore the collective dynamical behavior of biaxial particles in nonequilibrium. For spherical and uniaxial particles, earlier derived dynamical density functional theories are recovered as special cases. Our study is motivated by recent experimental progress in preparing colloidal particles with many different biaxial shapes., Comment: 9 pages, 1 figure

International audience; Crystallization near structured substrates is explored by extensive Brownian dynamics computer simulations of two-dimensional equimolar binary colloidal suspensions. The particles are interacting via repulsive dipole-dipole forces. The two species have different (big and small) dipole moments which are tunable by an external magnetic field. A quench is realized by a sudden drastic increase of the magnetic field which formally corresponds to a quench to zero temperature. After the quench the equilibrium state is an alternating square lattice which coincides exactly with that imposed by the external wall. The relaxation behavior following the quench is explored. The amount of local crystallites with triangular and square symmetry is monitored as a function of time for different initial temperatures. It found that the number and structure of crystallites near the walls strongly depend on the wall pattern. Even though local square structures are favored energetically and the equilibrium state is an alternating square lattice, the number of triangular crystallites close to the wall which has outermost fixed small particles is significantly higher than in the unconfined case. The actual number of triangular clusters depends on the depth of the quench. This effect is not contained in classical nucleation theory.

The aim of this paper is to review and to preview some selected topics of crystal nucleation in colloidal suspensions. First we discuss how the structure of critical nuclei can be calculated by computer simulations, in particular how linear shear flow affects the size and shape of the critical nuclei. Second, we preview the possibilities to access heterogeneous crystal nucleation and dynamics of a crystal by using the recently developed formalism of dynamical density functional theory. In particular, data for global crystal heating are presented.

International audience; We outline the formalism of liquid integral equation theory for anisotropic interactions in two dimensions and subsequently apply this theory to one-component super-paramagnetic particles exposed to a tilted magnetic field. Inhomogeneous local ordering of the particles is observed for different in-plane directions. The anisotropy of the interaction as well as of the liquid structure is increased by increasing the tilt angle. Furthermore, the particles favor an alignment in direction of the in-plane component of the magnetic field. For increasing tilt angle, the anisotropy of the structural correlations is qualitatively similar to that of the corresponding solid lattice which is stable at lower temperatures. However, the mean-square displacements behave qualitatively different in the solid and fluid phases as a function of the tilt angle.

We study a mixture of hard sphere colloidal particles and non-adsorbing polymers exposed to a plane wave external potential which represents a three-dimensional standing laser field. With computer simulations and density functional theory we investigate the structure and phase behaviour using the simple Asakura-Oosawa model. For varying laser wavelength λ we monitor the emergence of structure in response to the external field, as measured by the amplitude of the oscillations in the one-body density distribution. Between the ideal gas limit for small λ and the bulk limit of large λ there is a non-monotonic crossover that is governed by commensurability of λ and the colloid diameter. The theoretical curves are in good agreement with simulation results. Furthermore, the effect of the periodic field on the liquid-vapour transition is studied, a situation that we refer to as laser-induced condensation. Above a threshold value for λ the theoretical phase diagram indicates the stability of a ‘stacked’ fluid phas...

In the seminal approach of Car and Parrinello, published in 1985 [1], molecular dynamics simulations of classical ions were combined with quantum mechanical density functional theory for the electr...