Nonlocal potentials in independent-electron models

This note summarizes the motivation for extending current density-functional theory to include nonlocal one-electron potentials, and proposes methodology for practical calculations. The theoretical model, orbital functional theory, has been shown to be exact in principle for the general N-electron problem, but must depend in practice on a parametrized correlation energy functional. The discussion here is intended to honor Lee Allen and to bring up to date some conversations that we began in 1954.