Computational chemistry is a branch of
chemistry that uses
computer simulation to assist in solving chemical problems. It uses methods of
theoretical chemistry, incorporated into efficient
computer programs, to calculate the structures and properties of
molecules and solids. Its necessity arises from the fact that — apart from relatively recent results concerning the
hydrogen molecular ion (see references therein for more details) — the quantum
many-body problem cannot be solved analytically, much less in closed form. While computational results normally complement the information obtained by chemical
experiments, it can in some cases predict hitherto unobserved chemical
phenomena. It is widely used in the design of new drugs and materials.