a College of Physical Science and Technology, Sichuan University, Chengdu 610064, China; b Department of Physics, Beijing Normal University, Beijing 100875, China
Abstract A generalized continuous time random walk model which is dependent on environmental damping is proposed in which the two key parameters of the usual random walk theory: the jumping distance and the waiting time, are replaced by two new ones: the pulse velocity and the flight time. The anomalous diffusion of a free particle which is characterized by the asymptotical mean square displacement is realized numerically and analysed theoretically, where the value of the power index is in a region of . Particularly, the damping leads to a sub-diffusion when the impact velocities are drawn from a Gaussian density function and the super-diffusive effect is related to statistical extremes, which are called rare-though-dominant events.
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