  When modelling stars with masses larger than 1.2Msun with no observed
chemical peculiarity, atomic diffusion is often neglected because, on its own,
it causes unrealistic surface abundances compared with those observed. The
reality is that atomic diffusion is in competition with other transport
processes. The purpose of this study is to quantify the opposite or conjugated
effects of atomic diffusion and rotationally induced mixing in stellar models
of low mass stars. Our second goal is to estimate the impact of neglecting both
rotational mixing and atomic diffusion in stellar parameter inferences for
stars with masses larger than 1.3Msun. Using the AIMS code, we infer the masses
and ages of a set of representative artificial stars for which models were
computed with the CESTAM evolution code, taking into account rotationally
induced mixing and atomic diffusion, including radiative accelerations. We show
that for masses lower than 1.3Msun, rotation dominates the transport of
chemical elements, and strongly reduces the effect of atomic diffusion, with
net surface abundance modifications similar to solar ones. At larger mass,
atomic diffusion and rotation are competing equally. Above 1.44Msun, atomic
diffusion dominates in stellar models with initial rotation smaller than
80km.s-1 producing a chemical peculiarity which is not observed in
Kepler-legacy stars. This indicates that a transport process of chemical
elements is missing. Importantly, neglecting rotation and atomic diffusion
(including radiative accelerations) in the models, when inferring the
parameters of F-type stars, may lead to errors of 5%, 2.5% and 25% respectively
for stellar masses, radii and ages. Atomic diffusion (including radiative
accelerations) and rotational mixing should be taken into account in stellar
models in order to determine accurate stellar parameters.
