First-principles calculation of hydrogen diffusion barriers on Si(001)-2x1 surface

Barriers for hydrogen diffusion on Si(001)-2 x 1 surface along 12 elemental pathways have been studied by means of first-principles calculations. The calculations were performed based on density functional theory (DFT) with generalized gradient approximation (GGA). The calculated barriers of intra-row and intra-dimer hydrogen diffusion on clean surface are 10% and 11% lower than that experimentally observed, respectively. With the adjusted barrier and a known or reasonable assumed attempt frequency, the average hydrogen hopping time on Si(001)-2 x 1 surface at specific temperature can be estimated.