Editing Quantum chemistry (section)

==History==
Some view the birth of quantum chemistry as starting with the discovery of the [[Schrödinger equation]] and its application to the hydrogen atom. However, a 1927 article of [[Walter Heitler]] (1904–1981) and [[Fritz London]] is often recognized as the first milestone in the history of quantum chemistry.<ref>{{Cite journal |last1=Heitler |first1=W. |last2=London |first2=F. |date=1927 |title=Wechselwirkung neutraler Atome und homopolare Bindung nach der Quantenmechanik |url=http://dx.doi.org/10.1007/BF01397394 |journal=Zeitschrift für Physik |volume=44 |issue=6–7 |pages=455–472|doi=10.1007/BF01397394 |bibcode=1927ZPhy...44..455H }}</ref> This was the first application of quantum mechanics to the diatomic [[hydrogen molecule]], and thus to the phenomenon of the chemical bond.<ref>{{Cite book |last=Kołos |first=W. |chapter-url=https://doi.org/10.1007/978-94-009-0949-6_8 |title=Perspectives in Quantum Chemistry. Académie Internationale Des Sciences Moléculaires Quantiques/International Academy of Quantum Molecular Science |publisher=Springer |year=1989 |volume=6 |location=Dordrecht |chapter=The Origin, Development and Significance of the Heitler-London Approach|pages=145–159 |doi=10.1007/978-94-009-0949-6_8 |isbn=978-94-010-6917-5 }}</ref> However, prior to this a critical conceptual framework was provided by [[Gilbert N. Lewis]] in his 1916 paper ''The Atom and the Molecule'',<ref>{{Cite journal |last=Lewis |first=G.N. |title=The Atom and the Molecule |url=http://dx.doi.org/10.1021/ja02261a002 |journal=[[Journal of the American Chemical Society]] |date=1916 |volume=38 |issue=4 |pages=762–785|doi=10.1021/ja02261a002 |bibcode=1916JAChS..38..762L }}</ref> wherein Lewis developed the first working model of [[Valence electron|valence electrons]]. Important contributions were also made by Yoshikatsu Sugiura<ref>{{Cite journal |last=Sugiura |first=Y. |date=1927 |title=Über die Eigenschaften des Wasserstoffmoleküls im Grundzustande |url=https://link.springer.com/article/10.1007/BF01329207 |journal=Zeitschrift für Physik |volume=45 |issue=7–8 |pages=484–492|doi=10.1007/BF01329207 |bibcode=1927ZPhy...45..484S }}</ref><ref>{{Cite journal |last=Nakane |first=Michiyo |date=2019 |title=Yoshikatsu Sugiura's Contribution to the Development of Quantum Physics in Japan |url=https://onlinelibrary.wiley.com/doi/10.1002/bewi.201900007 |journal=Berichte zur Wissenschaftsgeschichte |volume=42 |issue=4 |pages=338–356|doi=10.1002/bewi.201900007 |pmid=31777981 }}</ref> and S.C. Wang.<ref>{{Cite journal |last=Wang |first=S. C. |date=1928-04-01 |title=The Problem of the Normal Hydrogen Molecule in the New Quantum Mechanics |url=https://link.aps.org/doi/10.1103/PhysRev.31.579 |journal=Physical Review |volume=31 |issue=4 |pages=579–586 |doi=10.1103/PhysRev.31.579|bibcode=1928PhRv...31..579W }}</ref> A series of articles by [[Linus Pauling]], written throughout the 1930s, integrated the work of Heitler, London, Sugiura, Wang, Lewis, and [[John C. Slater]] on the concept of valence and its quantum-mechanical basis into a new theoretical framework.<ref>{{Cite journal |last=Pauling |first=Linus |date=April 6, 1931 |title=The nature of the chemical bond. Application of results obtained from the quantum mechanics and from a theory of paramagnetic susceptibility to the structure of molecules |url=http://scarc.library.oregonstate.edu/coll/pauling/bond/papers/1931p.3.html |journal=[[Journal of the American Chemical Society]] |volume=53 |issue=4 |pages=1367–1400 |doi=10.1021/ja01355a027 |bibcode=1931JAChS..53.1367P |via=Oregon State University Library}}</ref> Many chemists were introduced to the field of quantum chemistry by Pauling's 1939 text ''The Nature of the Chemical Bond and the Structure of Molecules and Crystals: An Introduction to Modern Structural Chemistry'', wherein he summarized this work (referred to widely now as [[valence bond theory]]) and explained quantum mechanics in a way which could be followed by chemists.<ref>{{Cite book |last=Pauling |first=Linus |title=The Nature of the Chemical Bond and the Structure of Molecules and Crystals: An Introduction to Modern Structural Chemistry |publisher=Cornell University Press |year=1939 |edition=1st}}</ref> The text soon became a standard text at many universities. <ref>{{Cite web |last=Norman |first=Jeremy |title=Pauling Publishes "The Nature of the Chemical Bond" |url=https://historyofinformation.com/detail.php?id=3956 |access-date=July 11, 2023 |website=History of Information}}</ref> In 1937, [[Hans Hellmann]] appears to have been the first to publish a book on quantum chemistry, in the Russian <ref>{{cite book|year=1937|last1=Хельман|first1=Г.|title=Квантовая Химия|publisher=Главная Редакция Технико-Теоретической Литературы, Moscow and Leningrad}}</ref> and German languages.<ref>{{cite book|year=1937|last1=Hellmann|first1=Hans|title=Einführung in die Quantenchemie|publisher= Deuticke, Leipzig und Wien}}</ref> 

In the years to follow, this theoretical basis slowly began to be applied to chemical structure, reactivity, and bonding.  In addition to the investigators mentioned above, important progress and critical contributions were made in the early years of this field by [[Irving Langmuir]], [[Robert S. Mulliken]], [[Max Born]], [[J. Robert Oppenheimer]], [[Hans Hellmann]], [[Maria Goeppert Mayer]], [[Erich Hückel]], [[Douglas Hartree]], [[John Lennard-Jones]], and [[Vladimir Fock]].