The line-tension effects on heterogeneous nucleation are considered when a spherical lens-shaped nucleus is nucleated top of substrate and the bottom wall cavity. effect line tension barrier can be separated from usual volume term. As radius increases, decreases approaches that flat substrate. However, as cavity increases A small less active site than substrate, more In contrast, maximum radii or become comparable. Therefore, by tuning size cavity, optimized. These results will useful in...

The space-fixed genetic algorithm originally proposed by Niesse and Mayne [J. Chem. Phys. 105, 4700 (1996)] is modified used to study the lowest energy structure of small silicon clusters employing empirical interatomic potentials. In this new algorithm, a gradient-free simplex method, rather than conventional gradient-driven conjugate gradient minimization employed Mayne, selected virtue its flexibility applicability any form potentials for which calculation derivatives difficult. Using two...

We present detailed numerical results on the ground state structures of metallic clusters. The Gupta-type many-body potential is used to account for interactions between atoms in cluster. Both genetic algorithm technique and basin hopping method have been applied search global energy minima excellent agreement found both schemes gives credence optimized values obtained. For four monovalent one polyvalent metals studied this work within accuracy energies presented here, we find that predicted...

Line-tension-induced scenario of heterogeneous nucleation is studied for a lens-shaped nucleus with finite contact angle nucleated on spherical substrate and the bottom wall cavity. The effect line tension free energy critical can be separated from usual volume term. By comparing that nucleus, we find may have lower than when positive large, which similar to drying transition predicted by Widom [B. Widom, J. Phys. Chem. 99, 2803 (1995)]. Then, homogeneous rather will favorable. Similarly,...

We examine the surface tension and Tolman's length of a spherical drop using simplified Cahn-Hilliard model which has been used previously by author to calculate homogeneous nucleation rate. It is found that given difference bulk correlation lengths liquid vapour phases, negative for normal liquids. discuss briefly difficulty estimating from computer simulations.

Capillarity approximation is used to study the free-energy landscape of nucleation when an intermediate metastable phase exists. The critical nucleus that corresponds saddle point as well whole can be studied using this capillarity approximation, and various scenarios growth elucidated. In study, we consider a model in which stable solid nucleates within vapor liquid We predict composite consists core wetting layer pure nuclei exist depending not only on supersaturation relative but also...

Heterogeneous nucleation of a new bulk phase on flat substrate can be associated with the surface transition called wetting transition. When this heterogeneous occurs completely wettable zero contact angle, classical theory predicts that free-energy barrier vanishes. In fact, there always exists critical nucleus and as first-order prewetting will occur even when angle is zero. Furthermore, changes its character from below coexistence (undersaturation) to above (oversaturation) it crosses...

A generalized Young’s equation, which takes into account two corrections to the line tension by curvature dependence of liquid–vapor surface and contact angle intrinsic tension, is derived from thermodynamic free-energy minimization. The correction can be qualitatively estimated using Tolman’s formula. for nanometer-scale droplets analytical formula determined van der Waals interaction available. apparent this nano-droplets are as small nN, lead either a positive or negative tension....

This paper reports further simplification and improvement of a modified particle swarm optimizer (PSO) called the Multi-Species Particle Swarm Optimizer (MSPSO) proposed by author. MSPSO extends original PSO dividing spatially into multiple cluster species in multi-dimensional search space. Each explores different area space tries to find out global or local optima that area. Therefore it can be used locate all minima multi-modal functions parallel. The previous version relies strongly on...

The effects of line tension on the morphology a sessile droplet placed top convex spherical substrate are studied. is determined from global minimum Helmholtz free energy. contact angle between and expressed by generalized Young's formula. When positive large, jumps discontinuously to ${180}^{\ensuremath{\circ}}$, circular shrinks towards substrate, detaches forming if hydrophobic (i.e., large). This finding consistent with that predicted Widom [J. Phys. Chem. 99, 2803 (1995)]; induces...

Atomic force microscopy was used to measure the “roughness” exponents of rough porous silicon surfaces formed by electrochemical anodization. It found that Si have a self-affine fractal structure characterized roughness α=0.53–0.64, dimensions D =2.36–2.47 and growth exponent β=0.24 ±0.02.

A double-parabola model is used to calculate various properties of the critical droplet in homogeneous nucleation using Cahn-Hilliard non-classical theory, and results are compared with those predicted from classical theory due Becker Doring. The calculation can be performed mostly analytically, quantities characterized by two parameters: supersaturation which measures difference chemical potential two-phase coexistence, asymmetry thermodynamic liquid vapour phase. predictions do not differ...

The homogeneous nucleation and growth in a simplest two-dimensional phase field model is numerically studied using the cell dynamics method. whole process from to simulated shown follow closely Kolmogorov-Johnson-Mehl-Avrami (KJMA) scenario of transformation. Specifically time evolution volume fraction new stable found KJMA formula. By fitting formula directly simulation data, not only Avrami exponent but magnitude rate and, particular, incubation are quantitatively studied. modified plot...

The minimum free-energy path (MFEP) is the most probable route of nucleation process on multidimensional surface. In this study, phase-field equation used as a mathematical tool to deduce MFEP homogeneous nucleation. We use simple square-gradient functional with quartic local function an example and study time evolution single nucleus placed within metastable environment. integration performed using numerically efficient cell-dynamics method. By monitoring size free energy system...

The one- and two-electron ground-state energies of singly doubly charged silicon (Si) dots modelled by a sphere covered with dioxide layer embedded in various dielectric media can be calculated as functions the size thickness oxide extending work Allan et al Babic al. electron-self-polarization, electron - electron-polarization are treated first-order perturbation theory, taking confined free-electron state unperturbed state. By changing oxides or surrounding medium, applied voltage required...

The free-energy barrier of filling a spherical cavity having an inner wall various wettabilities is studied. morphology and free energy lens-shaped droplet are determined from the minimum energy. effect line tension on also Then, equilibrium contact angle generalized Young's equation. By increasing volume within cavity, changes with 180° to lens convex meniscus, where morphological complete drying transition occurs. further volume, meniscus concave. concave spreads over whole wall, resulting...

The size-dependent contact angle and the drying wetting morphological transition are studied with respect to volume change for a spherical cap-shaped droplet placed on substrate. line-tension effect is included using rigorous formula Helmholtz free energy in capillary model. A from occurs when substrate hydrophobic small, similar predicted flat In addition, wrapped hydrophilic large volume. depends size: it decreases as increases line tension positive, whereas negative. droplets stable...

The capillary flow of a Newtonian and incompressible fluid in an axially symmetric horizontal tube with non-slowly-varying cross section boundary slip is considered theoretically under the assumption that Reynolds number small enough for Stokes approximation to be valid. Combining equation hydrodynamic model assuming Hagen-Poiseulle flow, general formula derived. Using newly derived formula, imbibition time evolution meniscus tubes non-uniform sections such as conical tube, power-law-shaped...