Abnormal surface diffusion of particles under the action of an external time-periodic force

Abstract

Abstract. This paper delves into the abnormal surface diffusion of particles in an external time-periodic field. The relationship is studied of the surface diffusion enhancement as a function of the amplitude and frequency of external fields. It is shown that the diffusion coefficient can be significantly increased (by several orders of magnitude) by applying external time-periodic fields. The diffusion gain ratio stronglly depends on the surface temperature and on the external field amplitude and frequency.

Temperature-Abnormal Diffusivity in underdamped spatially periodic systems

“…At late times normal diffusion takes place. Dependence D(ω) is nonmonotonic here, agreeing with findings in [30]. D reaches a maximum near ω = ω 2 ≡ 2π/τ 2 .…”

“…This differs from monotonically decreasing D(ω) in regions I, II. Such a nonmonotonic dependence D(ω) was observed in [30,31]; the forcing studied was sinusoidal in time, its amplitude (indeed) corresponded to region III in terminology of this work.…”

“…The diffusion process at sufficiently late times is normal, σ 2 ∝ t 1 , however the diffusion coefficient D ′ = σ 2 /(2t ′ ) (abnormally) increases as the temperature decreases. In [30] it was seen that TAD is also possible at timeperiodic external forcing. At such forcing TAD was only observed in a limited interval of the forcing frequencies.…”

“…Underdamped 1D system was studied in [30], with a sinusoidal potential (same as Eq. 3 below) and sinusoidal in time forcing.…”

“…Definitions (8,9) differ from such in [16,22,25,[30][31][32] by extra factors of 2 appearing in the definition of t ′ , and consequently in T ′ and γ ′ as well. Current definition makes interpreting the results easier (t ′ = 1 corresponds to one oscillation period at small γ ′ ).…”