Effective average diffusion coefficient <Dbead> of the individual beads in a multi-bead model vs. the length of the observation interval Δt. With BD the dynamics of the mass-less beads is determined on short time scales by the fast thermal motion of the individual beads while over longer periods the beads have to follow the center-of-mass motion of the complete particle (filled symbols). Consequently, over long intervals Δt the effective average bead diffusion coefficient <Dbead>(Δt) converges to Dtr. Without HI the two underlying timescales are separated even further. When the mass of the beads is considered and an LD propagation is used then the apparent <Dbead> also decreases at very short observation intervals independent of whether HI are used or not.
Geyer BMC Biophysics 2011 4:7 doi:10.1186/2046-1682-4-7