  The determination of particle size by dynamic light scattering uses the
Stokes-Einstein relation, which can break down for nanoscale objects. Here we
employ a molecular dynamics simulation of fully solvated 1-5 nm carbon
nanoparticles for the refinement of the experimental data obtained for
nanodiamonds in water by using dynamic light scattering. We performed molecular
dynamics simulations in differently sized boxes and calculated nanoparticles
diffusion coefficients using the velocity autocorrelation function and
mean-square displacement. We found that the predictions of the Stokes-Einstein
relation are accurate for nanoparticles larger than 3 nm while for smaller
nanoparticles the diffusion coefficient should be corrected and different
boundary conditions should be taken into account.
