GROUND-STATE PROPERTIES OF HG-2 .2. A QUANTUM MONTE-CARLO STUDY

We have carried out variational and pure diffusion quantum Monte Carlo calculations for the Hg atom and the Hg-2 molecule. In the case of th e Hg atom we have calculated valence correlation energies for relativi stic and nonrelativistic 20-valence-electron pseudopotentials. The res ults are compared with those of conventional ab initio methods. For th e Hg-2 molecule we have used a 2-valence-electron pseudopotential toge ther with a core-polarization potential. The resulting round state pot ential energy curve agrees well with curves derived from configuration interaction calculations. Jastrow factors were found to be an efficie nt method to describe electron correlation in these systems.