A typical log(〈r²〉) versus log(t) graph whose slope is expected to be unity. The least squares best fit line (dashed lines) has a slope of 1.03 in the figure. The inset on the upper left corner shows the variation of mean square displacement of the center of the cluster as a function of time whose slope gives the diffusion coefficientDdefined in Eq. (3). The inset on the lower right corner shows the variation of (〈r²〉)/tas a function of timetwhich is expected to be a constant at long time as seen in Eq. (3) which also gives the diffusion coefficient.