Diffusion length of Ga on the GaAs(0 0 1)- (2 x 4) beta2 is investigated by a newly developed Monte Carlo-based computational method. The new computational method incorporates chemical potential of Ga in the vapor phase and Ga migration potential on the reconstructed surface obtained by ab initio calculations; therefore we can investigate the adsorption, diffusion and desorption kinetics of adsorbate atoms on the surface. The calculated results imply that Ga diffusion length before desorption decreases exponentially with temperature because Ga surface lifetime decreases exponentially. Furthermore, Ga diffusion length L along [1 (1) over bar 0] and [1 1 0] on the GaAs(0 0 1)-(2 x 4) beta2 are estimated to be L[(1 (1) over bar 0]) congruent to 700 nm and L-[1 1 0] congruent to 200 nm, respectively, at the incorporation-desorption transition temperature (T similar to 860 K). (C) 2062 Elsevier Science B.V. All rights reserved.