  A precision of order one percent is needed on the parameters of
exoplanet-hosts stars in order to correctly characterize the planets
themselves. This will be achieved by asteroseismology. It is important in this
context to test the influence on the derived parameters of introducing atomic
diffusion with radiative accelerations in the models. In this paper, we begin
this study with the case of the star 94 Ceti A. We performed a complete
asteroseismic analysis of the exoplanet-host F-type star 94 Ceti A, from the
first radial-velocity observations with HARPS up to the final computed best
models. This star is hot enough to suffer from important effects of atomic
diffusion, including radiative accelerations. We tested the influence of such
effects on the computed frequencies and on the determined stellar parameters.
We also tested the effect of including a complete atmosphere in the stellar
models. The radial velocity observations were done with HARPS in 2007. The low
degree modes were derived and identified using classical methods and compared
with the results obtained from stellar models computed with the Toulouse Geneva
Evolution Code (TGEC). We obtained precise parameters for the star 94 Ceti A.
We showed that including atomic diffusion with radiative accelerations can
modify the age by a few percents, whereas adding a complete atmosphere does not
change the results by more than one percent.
