Editing Crystal field theory (section)

{{Short description|Theory in condensed matter physics}}
In [[inorganic chemistry]], '''crystal field theory''' ('''CFT''') describes the breaking of [[degenerate energy levels|degeneracies]] of electron orbital states, usually ''d'' or ''f'' orbitals, due to a static electric field produced by a surrounding charge distribution (anion neighbors). This theory has been used to describe various spectroscopies of [[transition metal]] [[complex (chemistry)|coordination complexes]], in particular optical spectra (colors). CFT successfully accounts for some [[magnetic]] properties, [[Color of chemicals|colors]], [[hydration reaction|hydration]] [[enthalpy|enthalpies]], and [[spinel]] structures of transition metal complexes, but it does not attempt to describe bonding. CFT was developed by physicists [[Hans Bethe]]<ref>{{Cite journal|last=Bethe|first=H.|date=1929|title=Termaufspaltung in Kristallen|journal=Annalen der Physik|language=de|volume=395|issue=2|pages=133–208|doi=10.1002/andp.19293950202|issn=1521-3889|bibcode=1929AnP...395..133B}}</ref> and [[John Hasbrouck van Vleck]]<ref>{{cite journal | last1 = Van Vleck | first1 = J. | title = Theory of the Variations in Paramagnetic Anisotropy Among Different Salts of the Iron Group | journal = Physical Review | volume = 41 | issue = 2 | pages = 208–215 | year = 1932 | doi = 10.1103/PhysRev.41.208|bibcode = 1932PhRv...41..208V }}</ref> in the 1930s. CFT was subsequently combined with [[molecular orbital theory]] to form the more realistic and complex [[ligand field theory]] (LFT), which delivers insight into the process of [[chemical bonding]] in transition metal complexes. CFT can be complicated further by breaking assumptions made of relative metal and ligand orbital energies, requiring the use of [[inverted ligand field theory]] (ILFT) to better describe bonding.