In this paper, we discuss the results of some molecular dynamics simulations of a magnetized one component plasma, targeted to estimate the diffusion coefficient D⊥ in the plane orthogonal to the magnetic field lines. We find that there exists a threshold with respect to the magnetic field strength |B→|: for weak magnetic field, the diffusion coefficients scale as 1/|B→|2, while a slower decay appears at high field strength. The relation of this transition with the different mixing properties of the microscopic dynamics is investigated by looking at the behavior of the velocity autocorrelation.