A Preconditioner for Improved Fermion Actions
  SSOR preconditioning of fermion matrix inversions which is parallelized using a locally-lexicographic lattice sub-division, has been shown to be very efficient for standard Wilson fermions. We demonstrate here the power of this method for the Sheikholeslami-Wohlert improved fermion action and for a renormalization group improved action incorporating couplings of the lattice fermion fields up to the diagonal in the unit hypercube. 
N. Eicker, W. Bietenholz, A. Frommer, Th. Lippert, B. Medeke, and K.   Schilling