Compression of Gases at Moderate and High Densities

The cell method developed by Lennard-Janes and Devonshire is applied by using a two-potential model for the configurational energy to the determination of the equation of state of argon, nitrogen, and methane up to nearly half the liquid densities D1 the temperature range from 0 to l50°C. The LennardJones6-l2 potential and the Kihara hard core model with parameters determined from the second virial coefficients at low densities are used, respectively, for the calculation of the energy of the geometrically symmetric lattice and the excess potential energy arising from molecular motions. Calculated results compare favorably well with existing experimental data.