We carried out theoretical analyses based on ab initio calculations incorporates in which free energy of the vapor phase is incorporated in order to determine the initial growth kinetics of c-GaN on GaN(0 0 1)-(4 x 1). The feasibility of the theoretical approach had been confirmed by calculations of Ga adsorption-desorption transition temperature and transition beam equivalent pressures on the GaAs(0 0 1)-(4 x 2)beta 2 surface in our previous work [Y. Kangawa, T. Ito, A. Taguchi, K. Shiraishi, T. Ohachi, Surf. Sci. 493 (2001) 178]. The results of calculations suggest that no Ga adsorption occurs on the initial surface under typical growth conditions but that a Ga adsorption site appears after N adsorption on GaN(0 0 1)-(4 x 1). That is, in the initial growth stage of c-GaN on GaN(0 0 1)-(4 x 1), a N-adsorbed structure is formed and then Ga adsorbs on the N adatom. (c) 2006 Elsevier B.V. All rights reserved.