  We study the entanglement dynamics of the two two-level atoms coupling with a
single-mode polarized cavity field after incorporating the atomic centers of
mass classical harmonic vibrations with micro amplitudes and low frequencies.
We propose a quantitative vibrant factor to modify the concurrence of the two
atoms states. When the vibrant frequencies are very low, we obtain that: (i)
the factor depends on the relative vibrant displacements and the initial phases
rather than the absolute amplitudes, and reduces the concurrence to three
orders of magnitude; (ii) the concurrence increases with the increase of the
initial phases; (iii) the frequency of the harmonic vibration can be obtained
by measuring the maximal value of the concurrence during a small time. These
results indicate that even the extremely weak classical harmonic vibrations can
be monitored by the entanglement of quantum states.
