Using the projector-augmented plane wave method, the diffusion and dissociation processes of C2H2 molecules on the ferromagnetic body-centered cubic Fe(110) surface were studied and an investigation was made of the formation process of graphene created by C2H2 molecules. The most stable site for C2H2 on the Fe surface was a hollow site and its adsorption energy was -3.5eV. In order to study the diffusion process of the C2H2 molecule, the barrier height energies for the C atom, C2-dimer and CH as well as the C2H2 molecule were estimated using the nudged elastic band method. The barrier height energy for C2H2 was 0.71eV and this indicates that the C2H2 diffuses easily on this FM body-centered cubic Fe(110) surface. A further investigation was made of the two-step dissociation process of C2H2 on Fe. The first step was the dissociation of C2H2 into C2H and H, and the second step was that of C2H into C2 and H. Their dissociation energies were 0.9 and 1.2eV, respectively. These energies were relatively small compared to the dissociation energy 7.5eV of C2H2 into C2H and H in the vacuum. Thus, the Fe surface exhibited catalytic effects. Moreover, an investigation was made of the initial formation process of graphene upon increasing the coverage of C2H2. The formation process of the benzene molecule on the FM body-centered cubic (110) surface was also considered. It was found that there existed a critical coverage of C2H2 which characterized the beginning of the formation of the graphene.

First-Principles Analysis of C2H2 Molecule Diffusion and its Dissociation Process on the Ferromagnetic BCC-Fe(110) Surface. M.Ikeda, T.Yamasaki, C.Kaneta: Journal of Physics - Condensed Matter, 2010, 22[38], 384214