A VDOS Analysis of Fast Diffusion on Graphene Surfaces

Research has shown that water nanodroplets diffusing on graphene sheets have a higher-than-expected diffusivity. This is believed to be due to a surfing mechanism, in which the water droplets ride on vibrational waves of the surface like surfboards on water. Molecular dynamics simulations were used to study the energies of the system as well as performing an analysis of the vibrational density of states for the graphene sheet. The results showed that the water droplet has a greater impact on the optical phonons than on the acoustic phonons. Furthermore, a calculation on center-of-mass speed of the water nanodroplet showed that only a small fraction of the water droplet’s increase in kinetic energy comes from its diffusion.