Density dependent equations of state for metal, nonmetal, and transition   states for compressed mercury fluid
  Analytical equations of state are presented for fluid mercury in metal, nonmetal, and in metal-nonmetal transition states. Equations of state for metal and nonmetal states are simple in form but the complexities of transition state leads to a complex fourth-order equation. The interatomic potential function used to describe the metal state have a hard repulsive wall, and that of nonmetal state is the same as potential function of non-polar fluid with induced dipole intermolecular interaction. Metal-nonmetal transition occurs in the liquid density range 11-8 g/cm3, and a density dependent interaction potential which gradually changes from a pure metal interaction to a nonmetal interaction, on going from metal state to nonmetal state in the transition region, is used. Well-depth and the position of potential minimum are presented as temperature dependent quantities; their calculated values for the metal state are typically within 5.0% and 0.33% of the experimental value, respectively. The calculated well-depth for nonmetal state is smaller than the experimental value indicating the effect of high pressure PVT data used, which pushes a pair of mercury atom further together into the repulsive side. In the transition region, calculated well-depths are 2-3 order of magnitudes larger than for the metal state, and contain a sharp rising edge and a steep falling having a singularity characteristic of phase transition. 
M.H. Ghatee and M. Bahadori