1307.6963 (Nan Sheng et al.)

Asymmetrical free diffusion with orientation-dependence of molecules in
finite timescales    [PDF]

Nan Sheng, Yusong Tu, Pan Guo, Rongzheng Wan, Haiping Fang

Using molecular dynamics simulations, we show that free diffusion of a nanoscale particle (molecule) with asymmetric structure critically depends on the orientation in a finite timescale of picoseconds to nanoseconds. In a timescale of ~100 ps, there are ~10% more possibilities for the particle moving along the initial orientation than moving opposite to the orientation; and the diffusion distances of the particle reach ~1 nm. We find that the key to this observation is the orientation-dependence of the damping force to the moving of the nanoscale particle and a finite time is required to regulate the particle orientation. This finding extends the work of Einstein to nano-world beyond random Brownian motion, thus will have a critical role in the understanding of the nanoscale world.

View original: http://arxiv.org/abs/1307.6963