Mobility of atomic chains on channeled surfaces

We investigate the mobility of one-dimensional n-adatom chains deposited on the (110)(1x2) metal surface. All known diffusion mechanisms are taken int o account; dissociation-reassociation processes are also included. On the m issing-row reconstructed surface, diffusion may proceed via the leapfrog me chanism. Through a set of analytical calculations we find the law describin g leapfrog-induced diffusion for every n. It turns out that in a wide range of n, at typical experimental temperatures, chain mobility may be independ ent of the chain length. As a consequence, even long chains are expected to display a significant mobility. On the contrary, on the (110)(1x1) surface s, where the leapfrog diffusion mechanism is not present, tetramers are alr eady practically motionless. (C) 2000 American Institute of Physics. [S0021 -9606(00)70425-9].