content_image/357926.jpg
<img src='content_image/357926.jpg'>

motions covering all long outer tubes. 

For low thermal gradients (below ∼ 1 K/nm), steady velocity state is expected to be achieved for even longer outer tubes. By reducing the temperature, a decreased in the friction is expected since nanotube vibrations (one of the causes of energy dissipation) are reduced. This is indeed observed in the γ values of the fitted parameters for the cases of 7 and 17 K/nm. Thus, we expect a decreasing of the γ value for lower thermal gradients than 7 K/nm. 

Since we have not performed molecular dynamics simulations for low thermal gradients (below 1 K/nm), which provide the necessary parameters for Eq. (1), we can only estimate the behavior for such cases. The estimation is done by numerically integration Eq. (1) for different parameters of γ and α . The parameter F$_{vdw}$ will not change since we are not 

