Phase characterization Monte Carlo simulations

The analysis of phase diagrams in systems such as Cu-Au has been undertaken from the perspective of Monte Carlo simulation. In this problem consider an fee lattice characterized by an effective Hamiltonian of the form... 

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. 

The micropore structure can be determined by several methods such as immersion calorimetry, small-angle X-ray scattering (SAXS) high resolution transmission electron microscopy (HRTEM) and s- and liquid-phase adsorption, among which the most widely us is gas adsorption[7]. The pore structure of activated carbon is usually characterised in terms of the pore size distribution (PSD), perhaps die most imporlant aspect of characterization of die structural heterogeneity of porous solids used in industrial applications. This PSD could be obtained as an arbitrarily chosen form such as, for instance, mma or C ssian distribution[8]. For a local isodierm one may choose traditional mmlels, statistical mechanical methods such as DFT, or, most accurate for micropores, methods based on Monte Carlo simulation. 

The focus in development of the OPLS-UA model was on the non-bonded parameters, which historically had been the most problematic, and the new approach was to perform large numbers of Monte Carlo statistical mechanics simulations of pure liquids for their refinement. This advance was made possible by increases in computer resources and the development of flexible, efficient software, namely, the BOSS program and its predecessors, that allowed rapid setup of simulations for new systems. The key point was that a principal application of such force fields was in condensed-phase simulations including protein dynamics, and testing of the force fields on prediction of well-characterized condensed-phase properties was needed. Minimally, reproduction of liquid densities and heats of vaporization provides some confidence in both the size of the molecules and the strengths of their intermolecular interactions. Furthermore, these quantities are obtained from both experiment and simulation with high precision. 

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