New developments in classical density functional theory

Evans, Robert; Oettel, Martin; Roth, Roland; Kahl, Gerhard

doi:10.1088/0953-8984/28/24/240401

Cited by 87 publications

(83 citation statements)

References 51 publications

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“…This is a good approximation, as we find that the difference between isotropic and anisotropic gradients is a small correction for relevant conditions, typically one or two orders smaller in magnitude compared to all other contributions [43]. The adiabatic force field can be expressed as the negative gradient of the local excess (over ideal gas) chemical potential, which within classical density functional theory [7,39] (see appendix B for a brief overview) is given via functional differentiation of the excess Helmholtz free…”

Section: Phase Behaviourmentioning

confidence: 99%

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Phase coexistence of active Brownian particles

et al. 2019

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We investigate motility-induced phase separation of active Brownian particles, which are modeled as purely repulsive spheres that move due to a constant swim force with freely diffusing orientation. We develop on the basis of power functional concepts an analytical theory for nonequilibrium phase coexistence and interfacial structure. Theoretical predictions are validated against Brownian dynamics computer simulations. We show that the internal one-body force field has four nonequilibrium contributions: (i) isotropic drag and (ii) interfacial drag forces against the forward motion, (iii) a superadiabatic spherical pressure gradient and (iv) the quiet life gradient force. The intrinsic spherical pressure is balanced by the swim pressure, which arises from the polarization of the free interface. The quiet life force opposes the adiabatic force, which is due to the inhomogeneous density distribution. The balance of quiet life and adiabatic forces determines bulk coexistence via equality of two bulk state functions, which are independent of interfacial contributions. The internal force fields are kinematic functionals which depend on density and current, but are independent of external and swim forces, consistent with power functional theory. The phase transition originates from nonequilibrium repulsion, with the agile gas being more repulsive than the quiet liquid. arXiv:1910.06022v2 [cond-mat.stat-mech]

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Section: Phase Behaviourmentioning

confidence: 99%

“…(3). From inserting the Fourier series (26) for ρ into (45) and using (38) and (39) we obtain the swim pressure as…”

Section: F Spherical Superadiabatic Pressurementioning

confidence: 99%

Phase coexistence of active Brownian particles

et al. 2019

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“…Classical density functional theory is a statistical mechanical tool for a description of structure and thermodynamics of molecular inhomogeneous systems [46,49,50]. Within DFT, all the information about the fluid micro-scopic properties is embraced in the intrinsic free energy functional F[ρ(r)] of the fluid one-body density (density profile) ρ(r) and which is typically separated into the ideal gas and excess contributions…”

Section: Model and Density Functional Theorymentioning

confidence: 99%

Symmetry-breaking morphological transitions at chemically nanopatterned walls

Pospíšil¹,

Láska²,

Malijevský³

2019

Phys. Rev. E

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We study the structure and morphological changes of fluids that are in contact with solid composites formed by alternating and microscopically wide stripes of two different materials. One type of the stripes interacts with the fluid via long-ranged Lennard-Jones-like potential and tends to be completely wet, while the other type is purely repulsive and thus tends to be completely dry. We consider closed systems with a fixed number of particles that allows for stabilization of fluid configurations breaking the lateral symmetry of the wall potential. These include liquid morphologies corresponding to a sessile drop that is formed by a sequence of bridging transitions that connect neighboring wet regions adsorbed at the attractive stripes. We study the character of the transitions depending on the wall composition, stripes width, and system size. Using a (classical) nonlocal density functional theory (DFT), we show that the transitions between different liquid morphologies are typically weakly first-order but become rounded if the wavelength of the system is lower than a certain critical value Lc. We also argue that in the thermodynamic limit, i.e., for macroscopically large systems, the wall becomes wet via an infinite sequence of first-order bridging transitions that are, however, getting rapidly weaker and weaker and eventually become indistinguishable from a continuous process as the size of the bridging drop increases. Finally, we construct the global phase diagram and study the density dependence of the contact angle of the bridging drops using DFT density profiles and a simple macroscopic theory. arXiv:1912.12111v1 [cond-mat.stat-mech]

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“…In our model, the particles are subjected to a feedback potential driving them away from their previous positions. Using Brownian dynamics computer simulations and dynamical density functional theory [70][71][72][73][74][75], we show that this repulsive feedback leads to selforganization of the particles into a moving band structure reminiscent of a traveling wave. Remarkably, this ordering takes place despite the absence of any attractive interactions in the system, for which static band formation is known to occur [76,77].…”

Section: Introductionmentioning

confidence: 99%

Traveling band formation in feedback-driven colloids

2019

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Using simulation and theory we study the dynamics of a colloidal suspension in two dimensions subject to a time-delayed repulsive feedback that depends on the positions of the colloidal particles. The colloidal particles experience an additional potential that is a superposition of repulsive potential energies centered around the positions of all the particles a delay time ago. Here we show that such a feedback leads to self-organization of the particles into traveling bands. The width of the bands and their propagation speed can be tuned by the delay time and the range of the imposed repulsive potential. The emerging traveling band behavior is observed in Brownian dynamics computer simulations as well as microscopic dynamic density functional theory (DDFT). Traveling band formation also persists in systems of finite size leading to rotating traveling waves in the case of circularly confined systems. arXiv:1904.08373v2 [cond-mat.soft]

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New developments in classical density functional theory

Cited by 87 publications

References 51 publications

Phase coexistence of active Brownian particles

Phase coexistence of active Brownian particles

Symmetry-breaking morphological transitions at chemically nanopatterned walls

Traveling band formation in feedback-driven colloids

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