An atomistic fourth-order virial equation of state for Argon from first principles calculations

The virial equation of state up to fourth order for Argon is constructed using highly accurate ab initio two- and three-body potentials. Experimental EOS data is reproduced within at least ±1.7% in terms of pressure near the critical point and significantly better for larger volumes (less than ±0.5% or ±0.025 MPa for 200 cm3 mol−1 or larger). The critical temperature of Tc = 148.8 K obtained for the liquid-vapor phase equilibrium is in excellent agreement with the experimental value of 150.687 K.

50Highlights► We construct a fourth-order virial equation of state for Argon. ► Cluster integrals are computed from ab initio two- and non-additive three-body potentials. ► Agreement with experimental data up to near the critical point is excellent. ► The critical temperature is computed to 148.8 K (experimental 150.687 K).