Molecular dynamics simulations were used to study the effect of rotational degrees of freedom on the surface diffusion of C60 on graphene substrate (table 12). It was shown that there was an intermediate temperature range within which the rotational degrees of freedom played an important role in enhancing the molecular mobility in the system, which was in contrast to both the low-and high-temperature regimes in which the rotational degrees of freedom showed little influence. The underlying mechanistic origin for the enhancement was further analyzed and it was found that, in this regime, the rotational degrees of freedom provided alternative routes for the admolecule to overcome the energy barriers of the system, leading to a quasi-continuous Brownian motion on the surface.

Effect of Rotational Degrees of Freedom on Molecular Mobility. Jafary-Zadeh, M., Reddy, C.D., Zhang, Y.W.: Journal of Physical Chemistry C, 2013, 117[13], 6800-6

Table 12

Arrhenius parameters for C60 diffusion on graphene

SJ: single jumps, QCBM: quasi-continuous Brownian motion, BLBM: ballistic-like Brownian motion