Molecular simulation study of the structural properties in InxGa1−xAs alloys: comparison between Valence Force Field and Tersoff potential models

The thermodynamic and structural properties of compound semiconductor alloys have been generally modelled using either the Valence Force Field model or the Tersoff potential model. This work compares the properties, such as lattice constant and bond length, of the InxGa1−xAs alloy as predicted by Monte Carlo simulations in the semigrand isothermal isobaric ensemble using both the potential models, with experimental data. The lattice constants are expected to follow the Vegard’s law at any given temperature. Valence Force Field model predicts bond length data which follows the experimentally determined values at 300 K; whereas the Tersoff model forecasts that the virtual crystal approximation will be followed. The VFF model, with its experimentally determined parameters, is found to be better for modelling the alloy at room temperature. The Tersoff model, with its fitted parameters, on the other hand predicts the effect of temperature on the microscopic structure of the alloy better. The parameters of the Tersoff potential characterizing the In–Ga interactions can be further improved to predict bond lengths more accurately.© Elsevie

Vapor–liquid phase coexistence curves for Morse fluids

Phase coexistence of Morse fluids is predicted for parameters in the range describing the behavior of metals using the grand-canonical transition matrix Monte Carlo method. The critical properties of the vapor–liquid equilibrium curves for three fcc metals, Al, Cu, and Au, and two bcc alkali metals, Na and K, are estimated and the critical temperature values are found to be in good agreement with the experimental data for the fcc metals considered but overestimated for the bcc metals. For Na, it was found that the critical density and vapor pressure as a function of temperature (below the critical temperature) estimates to be approximately concurrent with experimental results.© Elsevie

Vapor-liquid phase coexistence curves for Morse fluids

Phase coexistence of Morse fluids is predicted for parameters in the range describing the behavior of metals using the grand-canonical transition matrix Monte Carlo method. The critical properties of the vapor-liquid equilibrium curves for three fcc metals, Al, Cu, and Au, and two bcc alkali metals, Na and K, are estimated and the critical temperature values are found to be in good agreement with the experimental data for the fcc metals considered but overestimated for the bcc metals. For Na, it was found that the critical density and vapor pressure as a function of temperature (below the critical temperature) estimates to be approximately concurrent with experimental results.close242

Prediction of Vapor–Liquid Coexistence Data for <i>p</i>‑Cymene Using Equation of State Methods and Monte Carlo Simulations

A naturally occurring aromatic organic compound, <i>p</i>-cymene, finds applications as reaction intermediate, solvent in production of pharmaceuticals, fragrances, and fine chemicals. The experimental vapor liquid equilibria (VLE) data of <i>p</i>-cymene is available at pressures up to 537.4 kPa. In this study, the thermodynamic properties of <i>p</i>-cymene are determined using structure property correlations combined with equations of state (EoS) and molecular simulation techniques. Two molecular simulation techniques, Gibbs ensemble Monte Carlo (GEMC) and grand canonical-transition matrix Monte Carlo (GC-TMMC) have been employed for prediction of VLE. The estimates of properties, including vapor pressures, heats of vaporization, coexistence densities, and critical properties have been compared with available experimental data. The thermodynamic properties predicted by molecular simulations and also that obtained from Peng–Robinson (PR) and volume translated Peng–Robinson (VTPR) EoS are generally, in broad agreement with the experimental data. Further, GEMC results for coexistence densities and saturation vapor pressures are compared with that from GC-TMMC technique