Effective interaction potential and superfluid-solid transition of   spatially indirect excitons
  Using an adiabatic approximation we derive an effective interaction potentially for spatially indirect excitons. Using this potential and path integral Monte Carlo simulations we study exciton crystllization and the quantum melting phase transition in a macroscopic system of 2D excitons. Furthermore, the superfluid fraction is calculated as a function of density and shown to vanish upon crystallization. We show that the commonly used dipole model fails to correctly describe indirect excitons in quantum well structures. 
A. Filinov, P. Ludwig, M. Bonitz, and Yu. E. Lozovik