An elastic lattice in a random potential

Using Monte Carlo simulations, we study the properties of an elastic triangular lattice subject to a random background potential. As the cooling rate is reduced, we observe a rather sudden crossover between two different glass phases, one with exponential decay of correlations, the other with power-law decay. Contrary to predictions derived from continuum models, no evidence of a crossover in the mean-square displacement, B(r), from quadratic growth at small r, to logarithmic growth at large r is found.