The Coulomb interaction of an electron with each electron or nucleus in its environment is Fourier analyzed into components with wave vectors q. These components are classified as long (short) range when q is smaller (larger) than the electron’s wave number p. The contrasting characteristics of each class are discussed. Electron reflection at a material’s surface measures the effect of short-range components only.

• Received 9 March 1987

DOI:https://doi.org/10.1103/PhysRevA.36.1929