Dielectric screening and band-structure effects in low-energy photoemission

Nonlocal response of the surface to the incident light is included into an ab initio one-step photoemission theory. Surface-state normal emission spectra from Be(0001) and Al(100) are calculated by a full-potential scattering method and are found to agree well with the experiment in a wide energy range. The total exciting field is obtained within the random-phase approximation for jellium as well as for one-dimensional crystal models of the two surfaces. Material dependence of the multipole plasmon mode and strong effect of band structure on the photoyield is discussed.