  Here, an approach in terms of shot noise is proposed to study and
characterize surface diffusion and low vibrational motion when having
interacting adsorbates on surfaces. In what we call statistical limit, that is,
at long times and high number of collisions, one expects that diffusing
particles display an essential Markovian behavior. Accordingly, the action of
the pairwise potentials accounting for particle-particle collisions is
equivalent to considering a shot noise acting on a single particle. We call
this approach the interacting single adsorbate approximation, which gathers
three important advantages: (i) the dynamics underlying surface diffusion and
low vibrational motion can be easily understood in terms of relatively simple
stochastic processes; (ii) from our model, appropriate (and well justified)
working formulas are easily obtained, which explain the results arising from
more complicated (but commonly used) molecular dynamics simulations within the
Langevin formulation; and (iii), at the same time, it is less demanding
computationally than the latter type of calculations. In order to illustrate
the application of this model, numerical results are presented. Specially, our
model reproduces the experimental observation regarding the broadening of the
quasielastic peak ruling surface diffusion.
