molecular orbital theory

synonym: MO theory
https://doi.org/10.1351/goldbook.08841
Theory of quantum mechanics in which electrons in a molecule (lattice) are not assigned to particular bonds between atoms but move under the influence of all atoms.
Notes:
  1. Within the MO theory, the wave function of \(i\mbox{-}\rm{th}\) MO, \(\varphi_{i}\), is expressed as a weighted sum of all atomic orbitals, \(\chi_{r}\) (method known as the linear combination of atomic orbitals, LCAO): \[\varphi_{i} = \sum_{r=1}^{N}c_{ri}\chi_{r}\] where the coefficient \(c_{ri}\) is the contribution of the \(r\mbox{-}\rm{th}\) atomic orbital to the \(i\mbox{-}\rm{th}\) MO.
  2. MO theory is a counterpart of the valence bond theory in which electrons are assigned to individual bonds. MO theory fits perfectly for systems with delocalized electrons.
Source:
PAC, 2022, 94, 15. (Glossary of terms relating to electronic, photonic and magnetic properties of polymers (IUPAC Recommendations 2021)) on page 38 [Terms] [Paper]