Current progress in understanding alkali metal adsorption on metal surfaces

This paper reviews the current situation in the understanding of alkali adsorption on metal surfaces, with particular emphasis on recent structural discoveries. We start by describing the classical `Langmuir - Gurney' model for alkali adsorption and the challenges to it which arose in the mid 1980s. We then describe the results of structural studies from the early 1990s which provide a whole new set of phenomena to be explicable within the framework of a new paradigm, and discuss whether calculations based on density-functional theory constitute such a paradigm.