  We aim to probe the dynamic structure of the extended Solar neighbourhood by
calculating the radial metallicity gradients from orbit properties, which are
obtained for axisymmetric and non-axisymmetric potential models, of red clump
(RC) stars selected from the RAdial Velocity Experiment's Fourth Data Release.
Distances are obtained by assuming a single absolute magnitude value in
near-infrared, i.e. $M_{Ks}=-1.54\pm0.04$ mag, for each RC star. Stellar orbit
parameters are calculated by using the potential functions: (i) for the
MWPotential2014 potential, (ii) for the same potential with perturbation
functions of the Galactic bar and transient spiral arms. The stellar age is
calculated with a method based on Bayesian statistics. The radial metallicity
gradients are evaluated based on the maximum vertical distance ($z_{max}$) from
the Galactic plane and the planar eccentricity ($e_p$) of RC stars for both of
the potential models. The largest radial metallicity gradient in the $0<z_{max}
\leq0.5$ kpc distance interval is $-0.065\pm0.005$ dex kpc$^{-1}$ for a
subsample with $e_p\leq0.1$, while the lowest value is $-0.014\pm0.006$ dex
kpc$^{-1}$ for the subsample with $e_p\leq0.5$. We find that at $z_{max}>1$
kpc, the radial metallicity gradients have zero or positive values and they do
not depend on $e_p$ subsamples. There is a large radial metallicity gradient
for thin disc, but no radial gradient found for thick disc. Moreover, the
largest radial metallicity gradients are obtained where the outer Lindblad
resonance region is effective. We claim that this apparent change in radial
metallicity gradients in the thin disc is a result of orbital perturbation
originating from the existing resonance regions.
