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John Lennard-Jones

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John Edward Lennard-Jones (1894 - 1954) was a mathematician who held a chair of theoretical physics at Bristol University, and then a chair of theoretical science at Cambridge University. He may be regarded as the father of modern computational chemistry.

Lennard-Jones is well-known among scientists for his work on molecular structure, valency and intermolecular forces. Much research in these areas over several decades grew from a paper he published in 1929. His theories of liquids and of surface catalysis also remain influential. He wrote few papers, but was very innovative.

His main interest was in atomic and molecular structure, especially the forces between atomic particles, the nature of chemical bonds and such basic matters as why water expands when it freezes. Holding the first Chair of Theoretical Chemistry in the United Kingdom, he built up a research school applying to phenomena in physics and organic chemistry new concepts of quantum mechanics and the interactions of subatomic particles. The department drew on many notable scientists and mathematicians, including S.F. Boys, C.A. Coulson, P. Dirac (1933 Nobel Laureate who came with Jones from Bristol), G.G. Hall, A. Hurley, and J. Pople.

Atoms of a noble gas reach an equilibrium distance from each other when an attracting van der Waals force balances a repelling force the result of overlapping electron orbits. The strength at which these two forces balance is the so-called Lennard-Jones potential, which describes the separation of the atoms. Also named after him, the Lennard-Jones Laboratory houses the School of Chemistry and Physics at Keele University. The Royal Society of Chemistry awards a Lennard-Jones Medal and hosts the Lennard-Jones lecture each year. The name of LJ fluid (a Java Applet) honours him, too.

Keele University holds a collection of Lennard-Jones's published work. Professor C.A. Coulsonís collected lecture notes from 1928 - 1932, held in the Cambridge University Library, record Lennard-Jones's lectures. Coulson wrote 'I suspect that these are the first lectures on theoretical chemistry (or perhaps more accurately quantum chemistry) that had been given in Britain'. Lennard-Jonesís private papers are held at Churchill Archives Centre, in Cambridge.

Life in overview: 1894 Born in Leigh, Lancashire, and educated at Leigh Grammar School where he specialised in classics.
1912 Studied mathematics as an undergraduate at theUniversity of Manchester
1915-18 First World War service in the Royal Flying Corps
1919-22 Studies for Doctor of Science degree and lectures in Mathematics at Manchester University.
1922 Receives Doctor of Science degree at Manchester
1922-4 Research student with a Senior 1851 Exhibition at Trinity College, Cambridge, supervised by Ralph H. Fowler (1889-1944). Sydney Chapman, then Professor of Mathematics at Manchester, had been a Lecturer at Trinity in 1914, and advised Jones to apply there.
1924 Receives Doctor of Science degree at Cambridge. Proposes a semi-empirical interatomic force law.
1925 Marries Kathleen Lennard
1925-32 Professor of Theoretical Physics, Bristol University
1929 Paper [1] introduces Linear Combination of Atomic Orbitals approximation for molecular orbitals
1929 Brings to Bristol Gerhard Herzberg (1971 Nobel Laureate for chemistry) to study spectra of di- & poly-atomic molecules.
1930-2 Dean of the Faculty of Science, Bristol University
1931 Paper [2] introduces method for the atomic Self Consistent Field (SCF) equations. Proposes the Lennard-Jones potential
1932-53 Plummer Professor of Theoretical Science, Cambridge University. Founded the theoretical chemistry section of Cambridge University Chemical Laboratory.
1934 Paper [3] applies group theory to explain energies & structures of hydrocarbon free radicals
1933 Elected a fellow of the Royal Society
1934 Graduate student Charles Coulson (in 1972 Oxford University's first Professor of Theoretical Chemistry) completes PhD
1937 Paper [4] on conjugated hydrocarbons
1937 First Director of Cambridge University Mathematical Laboratory (now Cambridge University Computing Laboratory) with Maurice Wilkes as researcher.
1939 At outbreak of war, seconded as Chief Superintendent of Armament Research to the Ministry of Supply which took over the mathematical laboratory for ballistics calculations, developed a team of mathematicians for this purpose.
1942-5 Director-General of Scientific Research (Defence), Ministry of Supply
1942-7 Member of the Advisory Council of the Department of Scientific and Industrial Research.
1946 Knighted (KBE), returns to Cambridge
1947-53 Chairman of the Scientific Advisory Council at the Ministry of Supply
1948-50 President of the Faraday Society
1949 Paper [5] justifies use of diatomic orbitals only for valence electrons by showing the determinantal wave function to be invariant under unitary transformations that could accurately transform molecular orbitals into localized equivalent orbitals.
1950 Paper [6] completely defines molecular orbitals as eigenfunctions of the SCF Hamiltonian
1951 Graduate student John Pople (1998 Nobel Laureate for chemistry) completes PhD
1953 Awarded Royal Society's Davy Medal for work applying quantum mechanics to the theory of valency and analysis of the structure of chemical compounds
1953 Principal of University College of North Staffordshire (now Keele University). Corresponds with Linus Pauling about the need in England for more universities and institutes of technology.
1954 Honorary doctorate of science, Oxford University; dies aged 60.

Papers 1. Lennard-Jones, J.E. (1929) Trans.Faraday Soc. 25, 668.
2. Lennard-Jones, J.E. (1931) Proc.Camb.Phil.Soc. 27, 469.
3. Lennard-Jones, J.E. (1934) Trans.Faraday Soc. 30, 70.
4. Lennard-Jones, J.E. (1937) Proc.Roy.Soc. A158, 280.
5. Lennard-Jones, Sir John (1949) Proc.Roy.Soc. A198, 1,14.
6. Hall, G.G. and Lennard-Jones, Sir John (1950)Proc.Roy.Soc. A202, 155.

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