A study of the liquid–vapor interface of mercury: Computer simulation results

This paper extends our recently proposed pseudoatom theory for the liquid–vapor interface of simple metals to mercury. An important difference between mercury and the alkali metals is that in the former the metal–nonmetal transition takes place over a range of density positioned at much higher density than the critical density. A modified pseudoatom model, with an improved treatment of the metal–nonmetal transition, is presented. Using the modified effective Hamiltonian for the ions, Monte Carlo simulations of the liquid mercury surface have been carried out. The simulations reveal a highly structured liquid–vapor transition zone, with large amplitude density oscillations. The metal–nonmetal transition is found to play a critical role in determining the liquid–vapor interface structure, and it gives rise to a partial monolayer of nonmetallic atoms adsorbed on the metal surface. A detailed comparison of our results with the existing experimental and theoretical work, particularly the x-ray reflectance data of Lu and Rice, is presented.