DECORRELATING THE TOPOLOGY IN FULL QCD

We investigate the performance of the hybrid Monte Carlo algorithm in updating non-trivial global topological structures. We find that the h ybrid Monte Carlo algorithm has serious problems decorrelating the glo bal topological charge. This represents a warning which must be seriou sly considered when simulating full QCD, regardless of the number and type of fermions, with this or any similar algorithm. Simulated temper ing is examined as a means of accelerating the decorrelation.