  A classical-kind phase-space formalism is developed to address the tiny
intrinsic dynamical deviation from what is predicted by Wilczek-Zee theorem
during quantum adiabatic evolution on degeneracy levels. In this formalism, the
Hilbert space and the aggregate of degenerate eigenstates become the
classical-kind phase-space and a high-dimensional subspace in the phase-space,
respectively. Compared with the previous same study by a different method, the
current result is qualitatively different in that the first-order deviation
derived here is always perpendicular to the degeneracy subspace. A tripod
scheme Hamiltonian with two degenerate dark states is employed to illustrate
the adiabatic deviation with degeneracy levels.
