On Chemisorption Energy of a H Atom on DBA Surface

The one-dimensional tight-binding model and the Green's function (GF) method are used to calculate the chemisorption energy (ΔE) of a H atom on semi-infinite disordered binary alloys (SDBA) (NiCu, AuPt, NiPt) within the coherent-potential approximation (CPA) and the average T-matrix approximation (ATA). The chemisorption energy is calculated as a function of the concentration percentages of the two components of DBA. The results are as follows:
(I) for the system of H/Ni_xCu_1-x, ΔE decreases with the increasing of the Ni Concentration x, resulting in a more stable chemisorption, (Ⅱ) for the system of H/Au_xPt_1-x, H is preferentially adsorbed on a AuPt DBA at the concentration ratio of 25:75, (Ⅲ) for the system of H/Ni_xPt_1-x, the most unstable chemisorption occures at the concentration ratio of 20:80.
The calculation also shows that the results obtained by ATA are as good as those by CPA.