  0.8 GeV proton inelastic scatterings from $^{40}$Ar nucleus are analyzed
using an optical potential model in the Dirac coupled channel formalism. A
rotational collective model is used to obtain the transition optical potentials
for the low lying excited states of the rotational band. The optical potential
parameters of a Woods-Saxon shape and the deformation parameters of the excited
states are searched phenomenologically to reproduce the experimental
differential cross-section data by using the sequential iteration method. The
effect of a multistep process is investigated by including the channel coupling
between two excited states in addition to the couplings between the ground
state and the excited states. The calculated deformation parameters of the
excited states are compared with those obtained by using the nonrelativistic
calculations. The results of the Dirac coupled channel calculations are found
to show pretty good agreements with the experimental data of the ground state
and the low-lying excited states. The multistep excitation process via the
channel coupling with the second $2^+$ state is found to be important for the
excitation of the $4^+$ state at the inelastic scatterings from the deformed
nucleus, $^{40}$Ar.
