Investigation of rotational diffusion of a carbon nanotube by molecular dynamics

The rotational diffusion coefficient of a single carbon nanotube in fluid is calculated by equilibrium and nonequilibrium molecular dynamics (MD). The validity and accuracy of the MD simulations are checked on plenty of data points by varying the length and diameter of the nanotube. The three-dimensional (3D) coefficients are larger than the two-dimensional (2D) ones, both having nonnegligible deviations from the theoretical predictions [J. Chem. Phys. 1984, 81, 2047-2052]. By changing the parameter -C-Ar of Lennard-Jones potential, the interaction strength between carbon and argon atoms is also taken into account. A monotonic decrease of the coefficients for both 2D and 3D cases with the increase of -C-Ar can be observed. Our present work suggests that we must be cautious when using the literature theory in practical situations.