Variational Approach to the Ground State of the Electron-Hole Liquid

Abstract
In the many-body variational approach, accurate results are obtained for the ground-state properties of the isotropic electron-hole liquid. With the increase in hole mass, the system undergoes a transition to a state with ordered heavy particles. In the case of Ge under a large [111] strain, it is predicted that the metallic state is not stable relative to free excitons. The density dependence of e-h correlation obtained here compares favorably with the experimental estimates.