# Electronic structure

In quantum chemistry, **electronic structure** is the state of motion of electrons in an electrostatic field created by stationary nuclei.[1] The term encompasses both the wave functions of the electrons and the energies associated with them. Electronic structure is obtained by solving quantum mechanical equations for the aforementioned clamped-nuclei problem.

Electronic structure methods |
---|

Valence bond theory |

Coulson–Fischer theory Generalized valence bond Modern valence bond theory |

Molecular orbital theory |

Hartree–Fock method Semi-empirical quantum chemistry methods Møller–Plesset perturbation theory Configuration interaction Coupled cluster Multi-configurational self-consistent field Quantum chemistry composite methods Quantum Monte Carlo |

Density functional theory |

Time-dependent density functional theory Thomas–Fermi model Orbital-free density functional theory Linearized augmented-plane-wave method Projector augmented wave method |

Electronic band structure |

Nearly free electron model Tight binding Muffin-tin approximation k·p perturbation theory Empty lattice approximation GW approximation |

Electronic structure problems arise from the Born–Oppenheimer approximation. Along with nuclear dynamics, the electronic structure problem is one of the two steps in studying the quantum mechanical motion of a molecular system. Except for a small number of simple problems such as hydrogen-like atoms, the solution of electronic structure problems require modern computers.

Electronic structure problem is routinely solved with quantum chemistry computer programs. Electronic structure calculations rank among the most computationally intensive tasks in all scientific calculations. For this reason, quantum chemistry calculations take up significant shares on many scientific supercomputer facilities.

A number of methods to obtain electronic structures exist and their applicability varies from case to case.[2]

## References

- Simons, Jack (2003). "Chapter 6. Electronic Structures".
*An introduction to theoretical chemistry*(PDF). Cambridge, UK: Cambridge University Press. ISBN 0521823609. - H. F. Schaefer; et al. (1995). "1. The chemical applicability of standard methods in
*ab initio*molecular quantum mechanics". In Yarkony, David R. (ed.).*Modern Electronic Structure Theory*. Singapore: World Scientific. p. 3. ISBN 978-9810229870.