Monte Carlo simulations interfacial systems

When the two phases separate the distribution of the solvent molecules is inhomogeneous at the interface this gives rise to an additional contribution to the free energy, which Henderson and Schmickler treated in the square gradient approximation [36]. Using simple trial functions, they calculated the density profiles at the interface for a number of system parameters. The results show the same qualitative behavior as those obtained by Monte Carlo simulations for the lattice gas the lower the interfacial tension, the wider is the interfacial region in which the two solvents mix (see Table 3). 

A Monte Carlo simulation [102] of a system with short-range forces confirmed these notions. The correlation function clearly exhibited exponentially damped oscillations. From the ratio of the wavelength and correlation length, the value of y characterizing the system could be obtained from Eq. (35), and it was found that 1 > y > 0, indicating that the microemulsion was structured but weakly so. Within the mean-field calculation, however, this is still strong enough that the middle phase should not wet the oil/water interface. However, measurement of all three interfacial tensions within the simulation revealed that Antonow s rule was obeyed, so that the interface was indeed wetted by the middle phase, an effect clearly attributable to the fluctuations included in the simulation. 

Abraham, F. F. 1978. The interfacial density profile of a Lennard-Jones fluid in contact with a (100) Lennard-Jones wall and its relationship to idealized fluid/wall systems A Monte Carlo simulation. J. Ghent. Phys. 68 3713. 

It is important to propose molecular and theoretical models to describe the forces, energy, structure and dynamics of water near mineral surfaces. Our understanding of experimental results concerning hydration forces, the hydrophobic effect, swelling, reaction kinetics and adsorption mechanisms in aqueous colloidal systems is rapidly advancing as a result of recent Monte Carlo (MC) and molecular dynamics (MO) models for water properties near model surfaces. This paper reviews the basic MC and MD simulation techniques, compares and contrasts the merits and limitations of various models for water-water interactions and surface-water interactions, and proposes an interaction potential model which would be useful in simulating water near hydrophilic surfaces. In addition, results from selected MC and MD simulations of water near hydrophobic surfaces are discussed in relation to experimental results, to theories of the double layer, and to structural forces in interfacial systems. 

Molecular predictions of the properties of interfacial systems are now becoming possible as a result of rapid advances in liquid state chemical physics and computer technology. The objectives of this paper are 1) to review the general approaches and models used in Monte Carlo (MC) and molecular dynamics (MD) simulations of interfacial systems, 2) to describe and discuss results from selected simulation studies of interfacial water, and 3) to discuss the major limitations of these techniques and to offer suggestions for overcoming them. 

Simulation studies of the interfacial region between aqueous solutions and crystalline or liquid metals focused in recent years increasingly on the realistic description of the distinctive features of these systems. Both Molecular Dynamics and Monte Carlo computer simulations of such realistic models are nowadays a very active area of research. 

One typically finds that the order parameter of a continuous phase transition varies in the critical region as E - Ec) [53] or (T — Tc) [1, 33]. The numerical value of the critical exponent f depends only on a few physical properties, such as the dimension of the local variable (order parameter) in the Hamiltonian, the symmetry of the coupling between the local variables, and the dimensionality of the system (here 2D). This property is called universality [32, 33, 54]. Systems with identical critical behavior form one universality class. Only two examples have been reported for interfacial electrochemical systems In situ surface X-ray scattering (SXS) [53], chronocoulometry [55], and Monte Carlo (MC) simulations [56, 57] demonstrated... 

Numerical methods with different time- and length scales are employed and developed to investigate material properties and behaviors. Among them, molecular modeling can predict the molecular behaviors and correlate macroscopic properties of a material with various variables. The most popular techniques include molecular mechanics (MM), MD, and Monte Carlo (MC) simulation. These techniques are now routinely used to investigate the structure, dynamics, and thermodynamics of inorganic, biological, and polymer systems. They have recently been used to predict the thermodynamic and kinetic properties of nanoparticle-matrix mixtures, interfacial molecular structure and interactions, molecular dynamic properties, and mechanical properties. 

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