  The coefficient of diffusion of hydrogen in crystalline silicon is calculated
using tight-binding molecular dynamics. Our results are in good quantitative
agreement with an earlier study by Panzarini and Colombo [Phys. Rev. Lett. 73,
1636 (1994)]. However, while our calculations indicate that long jumps dominate
over single hops at high temperatures, no abrupt change in the diffusion
coefficient can be observed with decreasing temperature. The (classical)
Arrhenius diffusion parameters, as a consequence, should extrapolate to low
temperatures.
