Supercritical transition of Yukawa fluids identified by excess entropy.

Equilibrium molecular dynamical simulations of three-dimensional (3D) Yukawa fluids are performed to investigate thermodynamics and supercritical transition of 3D dusty plasma fluids. The normalized reduced excess entropy s_{ex}/s_{ex}^{m} of 3D Yukawa fluids (where s_{ex}^{m} is the excess entropy at the melting point) is calculated from their reduced excess internal energy u_{ex}, so that different variation trends of s_{ex}/s_{ex}^{m}∝Γ^{0.5} and ∝Γ^{2} are obtained at lower and higher temperatures, respectively. A fitting expression for s_{ex}/s_{ex}^{m} of 3D Yukawa fluids for all temperatures is proposed here, leading to the general expression of the excess internal energy. The relative deviation of s_{ex}/s_{ex}^{m} with respect to the power law scaling is introduced as Δ, so that the criterion of Δ=10% is proposed to determine the supercritical transition of 3D Yukawa fluids between the liquidlike and gaslike states. It is found that the supercritical transition points of 3D Yukawa fluids identified from Δ=10% well agree with the previous results from other criteria.