Molecular dynamics simulation of vapor-liquid equilibrium in 1-alkanol unary systems: a study of surface tension, density, and vapor pressure of TraPPE-UA force field

The vapor-liquid equilibrium of six primary alcohols (1-alkanol) ranging from methanol to 1-hexanol was studied using molecular dynamics simulations using TraPPE-UA potential fields. The critical temperature, density, pressure, boiling point, and enthalpy of vaporization were calculated for each system and compared with correlated experimental values and values obtained from Monte Carlo simulation in other literature. The effect of temperature on the density of the fluid and vapor phases and the surface tension of these systems was also studied and compared with experimental results. The experiment values from available literature for surface tension and density were correlated using modified fitting equations. The process of neglecting the long-range of Lennard-Jones interaction after a cut-off distance of 1.4nm was compared with taking them into account using PME correction. It was found that the neglected process significantly reduces the critical temperature values by about similar to 10%. Additionally, it was found that determining the critical temperature using surface tension gave slightly higher values that were closer to the experimental values in comparison with using the vapor-liquid density curve. The TraPPE-UA potential field was found to be significantly superior in predicting the critical temperature for all systems, and it was able to predict values with a margin of error of less than 2% of the experimental values.

Automated summary

The vapor-liquid equilibrium of six primary alcohols were studied using molecular dynamics simulations and compared with experimental results. The study found that neglecting the Lennard-Jones interaction significantly reduced the critical temperature values and determining the critical temperature using surface tension gave more accurate results. The TraPPE-UA potential field showed good accuracy in predicting the critical temperature.