  The Atom portal, udel.edu/atom, provides the scientific community with easily
accessible high-quality data about properties of atoms and ions, such as
energies, transition matrix elements, transition rates, radiative lifetimes,
branching ratios, polarizabilities, and hyperfine constants. The data are
calculated using a high-precision state-of-the-art linearized coupled-cluster
method, high-precision experimental values are used where available. All values
include estimated uncertainties. Where available, experimental results are
provided with references. This paper provides an overview of the portal and
describes the design as well as applied software engineering practices.
