Faddeev equations

Summary

The Faddeev equations are a system of linear equations for a quantum system of three particles with pairwise interactions. They split the three-body transition operator, or the wave function, into three components, one for each interacting pair. Unlike the direct three-body Lippmann–Schwinger equation, their kernel becomes compact after iteration. So Fredholm theory applies, and the equations have a unique solution in the generic case. They are the basis of the rigorous three-body scattering theory and of practical computations in nuclear and atomic physics.