The ground state of a substitutional and/or an interstitial hydrogen atom at the surface of solids is studied theoretically under the half-confinement approximation. The resultant wave function is not spherically symmetric, thus resulting in a nonzero dipole moment which points toward the solid, and the binding energy of the electron of the impurity-hydrogen atom is significantly lowered. The chemical activity of the confined atom and of the surface of solids is therefore greatly enhanced.

• Received 12 October 1989

DOI:https://doi.org/10.1103/PhysRevB.41.8180