Spectrum of the Dirac Operator and Inversion Algorithms with Dynamical Staggered Fermions

Complete spectra of the staggered Dirac operator $\text{Dirac}$ are determined in four-dimensional $SU(2)$ gauge fields with and without dynamical fermions. An attempt is made to relate the performance of multigrid and conjugate gradient algorithms for propagators with the distribution of the eigenvalues of~$\text{Dirac}$.