Configuration Interaction

Configuration Interaction (CI) is a post-Hartree-Fock quantum chemistry method that improves upon mean-field molecular orbital theory by treating electron correlation through a linear combination of electronic configurations. Introduced by Roothaan in 1960, CI corrects for the fundamental limitation of single-determinant theory by allowing the wavefunction to be a superposition of excited-state Slater determinants, systematically accounting for electron-electron interactions.