A density-functional study for the liquid-vapor coexistence curve of nitrogen fluid

The density functional theory for correlation of homonuclear diatomic fluids to predict the liquid vapor coexistence curve of nitrogen fluid was investigated. The pressure and chemical potential was calculated using thermodynamic integrations of the isotherm compressibility and of the excess internal energy. The predicted liquid-vapor coexistence curves and their diameters in scaled temperatures are studied. The two predictions from the thermodynamic integrations provide different equilibrium densities. It was found that the thermodynamic integration with T ^s=300K provided the better prediction of the liquid-vapor coexistence curves of N².