The performance of several common approximations for the exchange-correlation kernel within time-dependent density-functional theory is tested for elementary excitations in the homogeneous electron gas. Although the adiabatic local-density approximation gives a reasonably good account of the plasmon dispersion, systematic errors are pointed out and traced to the neglect of the wavevector depend...

We formulate a reduced order model for multi-layer, epitaxial growth of a thin film. The model describes layer-by-layer growth using three bulk (i.e. scalar) quantities per layer: average coverage ψ, average island number density n and average adatom density ρ for each layer. The model relies on simplifying assumptions on the geometry of the islands, as well as several approximations for the ph...

We develop a density functional for hard-sphere mixtures which keeps the structure of Rosenfeld’s fundamental measure theory (FMT) whilst inputting the Mansoori–Carnahan–Starling–Leland bulk equation of state. Density profiles for the pure hard-sphere fluid and for some binary mixtures adsorbed at a planar hard wall obtained from the present functional exhibit some improvement over those from t...

We present and analyze a penalization method which extends the the method of [2] to the case of a rigid body moving freely in an incompressible fluid. The fluid-solid system is viewed as a single variable density flow. The interface is captured by a color function satisfying a transport equation. The solid velocity is computed by averaging at every time the flow velocity in the solid phase. Thi...

Measurements of the moment of inertia by Kim and Chan have found that solid (4)He acts like a supersolid at low temperatures. To understand the order in solid 4(He), we have used path integral Monte Carlo simulations to calculate the off-diagonal long-range order (ODLRO) [equivalent to Bose-Einstein condensation (BEC)]. We do not find ODLRO in a defect-free hcp crystal of (4)He at the melting d...

In this paper we propose an extension of the Cahn method [1] to binary mixtures and study the problem of wetting near a two-phase critical point without any assumption on the form of intermolecular potentials. A comparison between Cahn’s method and later works by Sullivan [2,3], Evans et al [4,5] is made. By using an expression of the energy of interaction between solid surface and liquids prop...

Quantitative agreement with experimental data for adsorption of argon, krypton, and methane in high-silica zeolites is achieved with a molecular model, which (1) assumes pairwise additivity of intermolecular forces; (2) ignores partially concealed silicon atoms and lumps their dispersion energy with the oxygen atoms; (3) neglects energy induced by the weak electric field inside silicalite; (4) ...