Université de Fribourg

Local phase transitions in driven colloidal suspensions

Scacchi, Alberto ; Brader, Joseph M

In: Molecular Physics, 2018, vol. 116, no. 3, p. 378–387

Using dynamical density functional theory and Brownian dynamics simulations, we investigate the influence of a driven tracer particle on the density distribution of a colloidal suspension at a thermodynamic state point close to the liquid side of the binodal. In bulk systems, we find that a localised region of the colloid-poor phase, a ‘cavitation bubble’, forms behind the moving tracer....

Université de Fribourg

Flow induced crystallisation of penetrable particles

Scacchi, Alberto ; Brader, Joseph M

In: Journal of Physics: Condensed Matter, 2018, vol. 30, no. 9, p. 095102

For a system of Brownian particles interacting via a soft exponential potential we investigate the interaction between equilibrium crystallisation and spatially varying shear flow. For thermodynamic state points within the liquid part of the phase diagram, but close to the crystallisation phase boundary, we observe that imposing a Poiseuille flow can induce nonequilibrium crystalline ordering...

Université de Fribourg

Particle conservation in dynamical density functional theory

Heras, Daniel de las ; Brader, Joseph M ; Fortini, Andrea ; Schmidt, Matthias

In: Journal of Physics: Condensed Matter, 2016, vol. 28, no. 24, p. 244024

We present the exact adiabatic theory for the dynamics of the inhomogeneous density distribution of a classical fluid. Erroneous particle number fluctuations of dynamical density functional theory are absent, both for canonical and grand canonical initial conditions. We obtain the canonical free energy functional, which yields the adiabatic interparticle forces of overdamped Brownian motion....

Université de Fribourg

Driven colloidal fluids: construction of dynamical density functional theories from exactly solvable limits

Scacchi, Alberto ; Krüger, Matthias ; Brader, Joseph M

In: Journal of Physics: Condensed Matter, 2016, vol. 28, no. 24, p. 244023

The classical dynamical density functional theory (DDFT) provides an approximate extension of equilibrium DFT to treat nonequilibrium systems subject to Brownian dynamics. However, the method fails when applied to driven systems, such as sheared colloidal dispersions. The breakdown of DDFT can be traced back to an inadequate treatment of the flow-induced distortion of the pair correlation...

Université de Fribourg

Power functional theory for the dynamic test particle limit

Brader, Joseph M ; Schmidt, Matthias

In: Journal of Physics: Condensed Matter, 2015, vol. 27, no. 19, p. 194106

For classical Brownian systems both in and out of equilibrium we extend the power functional formalism of Schmidt and Brader (2013 J. Chem. Phys. 138 214101) to mixtures of different types of particles. We apply the framework to develop an exact dynamical test particle theory for the self and distinct parts of the van Hove function, which characterize tagged and collective particle motion. The...

Université de Fribourg

Microrheology close to an equilibrium phase transition

Reinhardt, Johannes ; Scacchi, A. ; Brader, Joseph M

In: The Journal of Chemical Physics, 2014, vol. 140, no. 14, p. 144901

We investigate the microstructural and microrheological response to a tracer particle of a two-dimensional colloidal suspension under thermodynamic conditions close to a liquid-gas phase boundary. On the liquid side of the binodal, increasing the velocity of the (repulsive) tracer leads to the development of a pronounced cavitation bubble, within which the concentration of colloidal particles is...