CALCULATIONS OF HYDROGEN DIFFUSION IN THE Ti(0001)-(1 x 1) SURFACE BY FIRST PRINCIPLES

Diffusion of H atom in the Ti(0001) outer-layer and inter-layer surface is studied using density functional theory based on generalized gradient approximation (GGA). The energy barriers for the hydrogen atom diffusion in different interstitial sites at the same layers or between adjacent layers are calculated. It is found that the energy barriers of H atom diffusion in the adjacent interstitial layers are bigger than that in the same interstitial layers. For the diffusion of H atom between adjacent interstitial layers, the diffusion between tetrahedral sites is easier than that between octahedral sites. While for diffusion of H atom between the same interstitial layers, the diffusion between tetrahedral sites is easier than that between tetrahedral and octahedral sites. Moreover, it is found that the most possible inside diffusion from hcp site of a hydrogen atom in the Ti( 0001) outer-layer goes through tetrahedral sites.