  We present a relativistic chiral mean field (RCMF) model, which is a method
for the proper treatment of pion-exchange interaction in the nuclear many-body
problem. There the dominant term of the pionic correlation is expressed in
two-particle two-hole (2p-2h) states with particle-holes having pionic quantum
number, J^{pi}. The charge-and-parity-projected relativistic mean field
(CPPRMF) model developed so far treats surface properties of pionic correlation
in 2p-2h states with J^{pi} = 0^{-} (spherical ansatz). We extend the CPPRMF
model by taking 2p-2h states with higher spin quantum numbers, J^{pi} = 1^{+},
2^{-}, 3^{+}, ... to describe the full strength of the pionic correlation in
the intermediate range (r > 0.5 fm). We apply the RCMF model to the ^{4}He
nucleus as a pilot calculation for the study of medium and heavy nuclei. We
study the behavior of energy convergence with the pionic quantum number,
J^{pi}, and find convergence around J^{pi}_{max} = 6^{-}. We include further
the effect of the short-range repulsion in terms of the unitary correlation
operator method (UCOM) for the central part of the pion-exchange interaction.
The energy contribution of about 50% of the net two-body interaction comes from
the tensor part and 20% comes from the spin-spin central part of the
pion-exchange interaction.
