Complex sentence: The R-matrix method is used in computational quantum mechanics to study scattering of positrons and electrons by atomic and molecular targets, a technique originally introduced by Eugene Wigner and Leonard Eisenbud in the 1940s.
Split into simpler sentences: The R-matrix method is used in computational quantum mechanics to study scattering of positrons and electrons by atomic and molecular targets. The fundamental idea was originally introduced by Eugene Wigner and Leonard Eisenbud in the 1940s.