Interactions of hydrogen with solid surfaces

Reactions of hydrogen with solid surfaces have become ones of the important subjects in the environment-related technologies, for example, as applications to the fuel cells. We review theoretical studies of hydrogen reactions on Cu(100), Cu(110) and Pd(111) surfaces and subsurfaces by quantum simulation method based on the first-principles calculations. By this method, we can obtain eigenenergies and three-dimensional eigenfunctions of hydrogen atomic motion in the vicinity of the surface. Based on the obtained results, we discuss quantum effects on excitation of hydrogen motion and diffusion within the surface and between the surface and subsurface. We especially focus on isotope effects arising from binding properties in the potential energy surfaces for the hydrogen atomic motion.