A set of coupled time-dependent Ginzburg-Landau equations (TDGL) for
superconductors of mixed d- and s-wave symmetry are derived microscopically
from the Gor'kov equations by using the analytical continuation technique. The
scattering effects due to impurities with both nonmagnetic and magnetic
interactions are considered. We find that the d- and s-wave components of the
order parameter can have very different relaxation times in the presence of
nonmagnetic impurities. This result is contrary to a set of phenomenologically
proposed TDGL equations and thus may lead to new physics in the dynamics of
flux motion.Comment: 22 pages, 6 figures are available upon request, to appear in Phys.
Rev.