Lennard-Jones interaction Liquid interface

Molecular dynamics has been used extensively to explore the solid-liquid interface. In one such study, a modified Lennard-Jones potential has been used to model this interaction in the spreading of a droplet [4], of the form... 

To illustrate the SS-LMBW methodology, we calculated the stractuie of the planar liquid/vapour as well as liquid/liquid interfaces of non-polar and polar molecular fluids hexane and methanol at ambient conditions. The site-site interaction potentials to appear in the closure (7) were specified in the form comprising the Coulomb and 12-6 Lennard-Jones terms,... 

As a modep) we assume an ideal infinite pore with radius a (fig. 1.32a). The liquid in the pore is not identical to that of the bulk because it is influenced by the interaction with the wall. The molar energy depends in some way on the distance to the wall, say = U r). e.g. according to a Lennard-Jones relationship. The pressure difference across the interface is given by the Laplace equation... 

The first computer simulation of liquid-solid coexistence, carried out by Hiwatari et al. was the molecular dynamics study of the fee (100) surface of a system of atoms interacting through truncated Lennard-Jones repulsive potentials. Subsequent molecular dynamics studies have looked at the same interface for Lennard-Jones and repulsive potentials, at the fee (111)... 

The interface between the droplet and the gas is not discontinuous the average molecular density decreases over a narrow region from the liquid side to the vapor. When the size of the droplet becomes sufhctently small compared with the thickness of the transition layer, the use of classical thermodynamics and the bulk surface tension become inaccurate the Kelvin relation and Laplace formula no longer apply. This effect has been studied by molecular dynamics calculations of the behavior of liquid droplets composed of 41 to 2(X)4 molecules that interact through a Lennard-Jones (LI) intermolecular potential (Thomp.son et al., 1984). The results of this analysis are shown in Fig. 9.5, in which the nondimensional pressure difference between the drop interior and the surrounding vapor (Pd — p)rr / ij is... 

A model of immiscible Lennard-Jones atomic solvents has been used to study the adsorption of a diatomic solute [71]. Subsequently, studies of solute transfer have been performed for atoms interacting through Lennard-Jones potentials [69] and an ion crossing an interface between a polar and a nonpolar liquid [72]. In both cases the potential of mean force experienced by the solute was computed the results of the simulation were compared with the result from the transition state theory (TST) in the first case, and with the result from a diffusion equation in the second case. The latter comparison has led to the conclusion that the rate calculated from the molecular dynamics trajectories agreed with the rate calculated using the diffusion equation, provided the mean-force potential and the diffusion coefficient were obtained from the microscopic model. 

The main objective of this work is to show that it is possible to model a LLI, using Lennard-Jones (LJ) potential and MD simulation technique. The idea is to simulate not a realistic system but a "simple model suitable for the study of the generic properties of an interface between non miscible liquids. To do that, we have chosen the MD simulation technique and periodic boundary conditions, for a system of particles interacting via a LJ potential already used for unstable mixtures. The results show that the LLI thus obtained is stable over the simulation time scale, as indicated by the density profiles. It is also interesting to note that the interfacial tension yielded by this model is in the range of the experimental values. The model and some computational details are described in section II. The results are reported in the following part and discussed in terms of stability and spatial extension of the LLI. The paper ends with some concluding remarks. 

---