Positional Disorder (Random Gaussian Phase Shifts) in the Fully   Frustrated Josephson Junction Array (2D XY Model)
  We consider the effect of positional disorder on a Josephson junction array with an applied magnetic field of f=1/2 flux quantum per unit cell. This is equivalent to the problem of random Gaussian phase shifts in the fully frustrated 2D XY model. Using simple analytical arguments and numerical simulations, we present evidence that the ground state vortex lattice of the pure model becomes disordered, in the thermodynamic limit, by any amount of positional disorder. 
Pramod Gupta and S. Teitel