Search results for "Carlo"
showing 10 items of 1845 documents
Heterogeneous nucleation of a droplet pinned at a chemically inhomogeneous substrate: A simulation study of the two-dimensional Ising case
2018
Heterogeneous nucleation is studied by Monte Carlo simulations and phenomenological theory, using the two-dimensional lattice gas model with suitable boundary fields. A chemical inhomogeneity of length b at one boundary favors the liquid phase, while elsewhere the vapor is favored. Switching on the bulk field Hb favoring the liquid, nucleation and growth of the liquid phase starting from the region of the chemical inhomogeneity are analyzed. Three regimes occur: for small fields, Hb bcrit, the critical droplet radius is so large that a critical droplet having the contact angle θc required by Young's equation in the region of the chemical inhomogeneity does not yet "fit" there since the base…
A Grand Canonical Monte Carlo Study of the N2, CO, and Mixed N2–CO Clathrate Hydrates
2018
In this paper we report the use of Grand Canonical Monte Carlo (GCMC) simulations to characterize the competitive trapping of CO and N2 molecules into clathrates, for various gas compositions in the temperature range from 50 to 150 K. The simulations evidence a preferential trapping of CO with respect to N2. This leads to the formation of clathrates that are preferentially filled with CO at equilibrium, irrespective of the composition of the gas phase, the fugacity, and the temperature. Moreover, the results of the simulations show that the small cages of the clathrate structure are always filled first, independent of either the guest structure or the temperature. This issue has been associ…
On the Ground State Structure of Adsorbed Monolayers: Can One Find them by Monte Carlo Simulation?
2002
While the classical ground state structure of an atomic monolayer adsorbed at a noncorrugated perfectly flat substrate trivially is a triangular lattice, the spacing being the minimum of the interatomic potential, nontrivial structures occur on corrugated substrates. This problem is exemplified for the (100) face of a face-centered cubic crystal, varying both the density of the adsorbed monolayer and the strength of the potential due to the surface. Increasing the density beyond that of the commensurate c(2 x 2) structure, incommensurate patterns become stable with “heavy” walls (HW) oriented along the face diagonals [including the “crossing heavy walls” (CRHW) phase]. It is shown that slow…
EDA: EXAFS data-analysis software package
2021
The EXAFS data-analysis software package EDA consists of a suite of programs running under a Windows operating system environment that is designed to perform all steps of conventional EXAFS data analysis such as extraction of the XANES/EXAFS parts of the X-ray absorption coefficient, Fourier filtering and EXAFS fitting using the Gaussian and cumulant models. The package also includes two advanced approaches which allow the reconstruction of the radial distribution function (RDF) from EXAFS based on the regularization-like method and the calculation of configuration-averaged EXAFS using a set of atomic configurations obtained from molecular-dynamics or Monte Carlo simulations.---- / / / ----…
Capillary condensation in the two-dimensional lattice gas: A Monte Carlo test of fluctuation corrections to the Kelvin equation
1997
A two-dimensional lattice gas model with nearest-neighbour attractive interaction confined in a strip of width L between two parallel boundaries at which an attractive short-range force acts is studied by Monte Carlo simulations, for cases where the system is in the wet phase near the critical wetting transition line for . We study the shift of the chemical potential of the transition in the strip as a function of L by thermodynamic integration methods, , and also obtain the thickness of the wetting film at the chemical potential at which capillary condensation occurs. In the range the data are consistent with a variation according to the Kelvin equation, , as well as with a shifted Kelvin …
Structural properties ofSi1−xGexalloys: A Monte Carlo simulation with the Stillinger-Weber potential
1995
The structural properties of binary silicon-germanium alloys are investigated by means of large-scale constant-pressure Monte Carlo simulations of the Stillinger-Weber model. At low temperatures, the binary-mixture phase separates into Si-rich and Ge-rich phases. The two-phase coexistence region is terminated by a critical point that belongs to the mean-field universality class. We also studied the structural properties of pure Si and Ge as well as the binary mixture. In particular, we found that the linear thermal expansions for both Si and Ge are in agreement with experiments, and that V\'egard's law is valid at temperatures above the critical point. Finally, we compare the bond-length an…
Interfacial tension of the isotropic-nematic interface in suspensions of soft spherocylinders.
2005
The isotropic to nematic transition in a system of soft spherocylinders is studied by means of grand canonical Monte Carlo simulations. The probability distribution of the particle density is used to determine the coexistence density of the isotropic and the nematic phases. The distributions are also used to compute the interfacial tension of the isotropic--nematic interface, including an analysis of finite size effects. Our results confirm that the Onsager limit is not recovered until for very large elongation, exceeding at least L/D=40, with L the spherocylinder length and D the diameter. For smaller elongation, we find that the interfacial tension increases with increasing L/D, in agreem…
Monte Carlo Simulations of Body Centered Cubic Alloys
1994
We illustrate the use of Monte Carlo simulations in the study of order-disorder phenomena in metallic alloys by presenting detailed work on a fairly realistic lattice model for iron aluminum. The model has been constructed based on recent measurements of effective interaction parameters and includes a description of the magnetism of iron within a Heisenberg Hamiltonian. We show that it reproduces the bulk phase diagram in a qualitatively correct way. Then internal antiphase boundaries and free surfaces in the (100)-direction are studied. An interfacial roughening transition is predicted as well as critical broadening of the profiles as the bulk approaches a second order transition. Nonstoec…
RANDOM SEQUENTIAL ADSORPTION ON A LINEAR LATTICE: EFFECT OF DIFFUSIONAL RELAXATION
1992
In this paper, the authors offer phenomenological arguments, supported by numerical Monte Carlo data, suggesting that the asymptotic large-time behavior of the coverage in the 1D lattice deposition of k-mers with k {gt} 3, accompanied by k-mer diffusion, is governed by the same mean-field dynamics as the lattice chemical reaction kA {yields} inert. The latter reaction is considered to occur with partial probability. The coverage in the deposition process approaches full saturation for any nonzero diffusion rate, and the void fraction decreases according to the power-law t{sup {minus}1/(k{minus}1)}.
Probing predictions due to the nonlocal interface Hamiltonian: Monte Carlo simulations of interfacial fluctuations in Ising films
2019
Extensive Monte Carlo simulations have been performed on an Ising ferromagnet under conditions that would lead to complete wetting in a semi-infinite system. We studied an L×L×D slab geometry with oppositely directed surface fields so that a single interface is formed and can undergo a localization-delocalization transition. Under the chosen conditions the interface position is, on average, in the middle of the slab, and its fluctuations allow a sensitive test of predictions that the effective interactions between the interface and the confining surfaces are nonlocal. The decay of distance dependent correlation functions are measured within the surface, in the middle of the slab, and betwee…