This article is about the many-body problem in quantum mechanics. For the n-body problem in classical mechanics, see n-body problem.

The many-body problem is usually posed in quantum mechanics, as the question of solving for more complex problems than the hydrogen atom — for example, the chemistry of all realistic molecules.

"It would indeed be remarkable if Nature fortified herself against further advances in knowledge behind the analytical difficulties of the many-body problem."

- Max Born, 1960

The many-body problem may be defined as the study of the effects of interaction between bodies on the behaviour of a many-body system. One of the preferred methods for solving the problem is simply to ignore it, i.e., pretend there are no interactions present.

Another approach is the canonical transformation technique .

See also

• Hartree-Fock approximation