No A1 (100) First Principles Study Of Surface Adsorption And Si In The Si (100) Surface Diffusion Of Molecular Dynamics Study

The adsorption of small molecules on metal surfaces is an important torpic in surface science, especially for NO adsorption. We investigated the adsorption of NO on Al(100) by employing the first-principles calculations based on density-functional theory. The optimized structures, binding energy, change of N-0 bond length of NO adsorption at some high-symmetry sites were calculated. We found that NO dissociated in the hollow site, the N and 0 atoms obtained from the dissociation were bound to the substrate, which is in good agreement with experimental results. We also found two metastable states, indicating NO may dissociate in these two sites under room temperature. Besides, we studied the density of states(DOS), projected density of states(PDOS), charge density of the system after NO dissociated. We point out the charge transfer from Al(100) to NO and the NO molecule orbitals hybridized with Al sp-band may be responsible for the NO dissociation.The diffusion of adatom on surface is significant to the thin film growth. The diffusion path, diffusion speed altogether contribute to the thin film growth. We studied the diffusion of Si adatom on Si(100) under high temperature by using molecular dynamics. We found a new diffusion path perpendicular to the dimmer rows, namely, Si adatom exchanged with one atom of the dimmer firstly, then the atom entered into trough, instead of Si adatom hopping into trough directly. Si adatom doesn't overcome high energy barrier by the new diffusion path, the occurrence possibility of which can not be neglected. We improve the idea that Si adatom is difficult to diffuse along the path perpendicular to dimmer rows, and weaken the anisotropy of Si adatom diffusion.