  Non-covalent interactions are essential in the description of soft matter,
including materials of technological importance and biological molecules. In
density-functional theory, common approaches fail to describe dispersion
forces, an essential component in noncovalent binding interactions. In the last
decade, great progress has been made in the development of accurate and
computationally-efficient methods to describe noncovalently bound systems
within the framework of density-functional theory. In this review, we give an
account of the field from a chemical and didactic perspective, describing
different approaches to the calculation of dispersion energies and comparing
their accuracy, complexity, popularity, and general availability. This review
should be useful to the newcomer who wants to learn more about noncovalent
interactions and the different methods available at present to describe them
using density-functional theory.
