This paper extends our recently proposed pseudoatom theory for the liquidndash;vapor interface of simple metals to mercury. An important difference between mercury and the alkali metals is that in the former the metalndash;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 metalndash;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 liquidndash;vapor transition zone, with large amplitude density oscillations. The metalndash;nonmetal transition is found to play a critical role in determining the liquidndash;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 xhyphen;ray reflectance data of Lu and Rice, is presented.
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