A behavior of a hydrogen atom of Pd_0.75Ag_0.25(111)

In this work, we calculate the adiabatic potential energy for the hydrogen atom on the Pd_0.75Ag_0.25(111) surface and in the subsurface using the first principles calculations based on the density functional theory. Moreover, we discuss the difference between the behaviors of the hydrogen atom on the Pd(111) and the Pd_0.75Ag_0.25 (111) surfaces by comparing the calculated potential energies. The results show that the potential energy minimum and an energy barrier for the hydrogen atom absorption into the bulk of the Pd_0.75 Ag_0.25(111) are lower than for the Pd(111) surface. It is shown that the potential energy rises when the hydrogen atom is located at a site where the nearest neighbor atoms include Ag atoms. In addition, the potential energy values Pd(111) surface and in the subsurface with lattice constant same as Pd_0.75Ag _0.25 (111), show that the decreasing of the potential energy caused by Ag alloying of the Pd (111) surface and is attributed to the increase of the lattice constant.