Impact of large cutoff-effects on algorithms for improved Wilson fermions

As a feasibility study for a scaling test we investigate the behavior of algorithms for dynamical fermions in the Nf=2 Schrödinger functional at an intermediate volume of 1fm4. Simulations were performed using HMC with two pseudo-fermions and PHMC at lattice spacings of approximately 0.1 and 0.07fm. We show that some algorithmic problems are due to large cutoff-effects in the spectrum of the improved Wilson-Dirac operator and disappear at the smaller lattice spacing. The problems discussed here are not expected to be specific to the Schrödinger functional.