atomic physics Atomic physics is the field of physics that studies atoms as an isolated system of electrons and an atomic nucleus. Atomic physics typically refers to the study of atomic structure and the interaction between atoms. It is primarily concerned wit ...

, close coupling is a

quantum mechanics Quantum mechanics is the fundamental physical Scientific theory, theory that describes the behavior of matter and of light; its unusual characteristics typically occur at and below the scale of atoms. Reprinted, Addison-Wesley, 1989, It is ...

method to calculate the multi-electronic atomic and

molecular structure Molecular geometry is the three-dimensional arrangement of the atoms that constitute a molecule. It includes the general shape of the molecule as well as bond lengths, bond angles, torsional angles and any other geometrical parameters that det ...

from fine structure to hyperfine structure levels and dynamic processes including

photoionization Photoionization is the physical process in which an ion is formed from the interaction of a photon with an atom or molecule. Cross section Not every interaction between a photon and an atom, or molecule, will result in photoionization. The prob ...

, collisional excitation and

ionization Ionization or ionisation is the process by which an atom or a molecule acquires a negative or positive Electric charge, charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged at ...

as well as autoionization and their inverse processes. In this method, the multi-electron systems are treated as a loosely interacting

electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...

with a target ionic or neutral atomic as well as molecular, in which the electrons are strongly interactive with each other. The interactive atomic or molecular complex system is reduced into a so-called (N+1) problem. Based on this scheme, the inter-channel interaction, that is,

configuration interaction Configuration interaction (CI) is a post-Hartree–Fock linear variational method for solving the nonrelativistic Schrödinger equation within the Born–Oppenheimer approximation for a quantum chemical multi-electron system. Mathemati ...

s (CI) are involved. Integrated with other techniques, especially the matrix techniques and multi-channel quantum defect theory, close-coupling method could provide precise structural and dynamical studies of atomic and molecular systems.

References

Atomic physics Electronic structure methods Quantum mechanics {{lattice-stub