  A soft-wall anti-de Sitter/QCD model with a modified five-dimensional metric
at the infrared region is constructed to obtain a nontrivial dilaton solution,
which incorporates the chiral symmetry breaking and linear confinement. By
taking the pion mass and decay constant as two input mass scales, the resulting
predictions for the resonance states of pseudoscalar, scalar, vector and
axial-vector mesons agree remarkably with the experimentally confirmed
resonance states. The effects of the quartic interaction term are investigated
by taking an appropriate sign and magnitude for maintaining the stability of
the bulk scalar potential. It is shown that such a simply modified soft-wall
anti-de Sitter/QCD model can lead to a consistent prediction for the mass
spectra of resonance states in the pseudoscalar, scalar, vector and
axial-vector mesons; the agreement with the experimental data is found to be
better than 10% for the excited meson states. The resulting pion form factor
also agrees well with the experimental data.
