Diffusion Boundary Condition at Surface Steps
  This Communication reports a geometrical factor that is necessary in the diffusion boundary condition across surface steps. Specifically, this factor relates adatom concentration to its spatial gradient at a surface step, and it describes the fraction of jump attempts that cross the step. In this Communication, the authors show that the factor is 1/\Pi using theoretical formulation and further verify the formulation using numerical simulations for triangular, square, and hexagonal surface lattices. 
Xiaobin Niu and Hanchen Huang
cond-mat.mtrl-sci cond-mat.mes-hall