Triple point of Yukawa systems

The molecular dynamics simulations of Yukawa (i.e., screened-Coulomb) systems that were applied to the regime of weak screening in an earlier study [S. Hamaguchi, R. T. Farouki, and D. H. E. Dubin, J. Chem. Phys. 105, 7641 (1996)] are extended to the strong screening regime. Transition temperatures at the fluid-solid phase boundary and the solid-solid phase boundary are obtained as functions of the screening parameter $\kappa =a/{\lambda }_D$ (i.e., the ratio of the Wigner-Seitz radius $a$ to the Debye length ${\lambda }_D$). The resulting phase diagram also covers the triple point—the intersection of the fluid-solid and solid-solid phase boundaries—at $\kappa =4.28\mathrm{}$ and $\Gamma =5.6\mathrm{}\times {10}^3,$ where Γ is the ratio of the Coulomb potential energy to the kinetic energy per particle (i.e., $\Gamma {=Q}^2/4\mathrm{}\pi {\epsilon }_{0}akT,$ where $Q$ is the charge of each Yukawa particle and $T$ is the system temperature). Yukawa systems serve as models for plasmas and colloidal suspensions of charged particulates.