  This work describes a new 1D hybrid approach for modeling atmospheric
pressure discharges featuring complex chemistry. In this approach electrons are
described fully kinetically using Particle-In-Cell/Monte-Carlo (PIC/MCC)
scheme, whereas the heavy species are modeled within a fluid description.
Validity of the popular drift-diffusion approximation is verified against a
"full" fluid model accounting for the ion inertia and a fully kinetic PIC/MCC
code for ions as well as electrons. The fluid models require knowledge of the
momentum exchange frequency and dependence of the ion mobilities on the
electric field when the ions are in equilibrium with the latter. To this end an
auxiliary Monte-Carlo scheme is constructed. It is demonstrated that the
drift-diffusion approximation can overestimate ion transport in simulations of
RF-driven discharges with heavy ion species operated in the $\gamma$ mode at
the atmospheric pressure or in all discharge simulations for lower pressures.
This can lead to exaggerated plasma densities and incorrect profiles provided
by the drift-diffusion models. Therefore, the hybrid code version featuring the
full ion fluid model should be favored against the more popular drfit-diffusion
model, noting that the suggested numerical scheme for the former model implies
only a small additional computational cost.
