Air mass (astronomy) and John Lennard-Jones: Difference between pages

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'''John Edward Lennard-Jones''' ([[October 27]], [[1894]] - [[November 1]], [[1954]]) was a [[mathematician]] who held a chair of theoretical physics at [[Bristol University]], and then a chair of [[theoretical chemistry|theoretical science]] at [[Cambridge University]]. He may be regarded as the father of modern [[computational chemistry]].

:{{Merge}} [[Air mass]]

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

In [[meteorology]], an air mass is a huge body of [[air]] that has basically constant characteristics throughout. These bodies of air usually extend for hundreds of miles of the [[Earth]]'s surface. [[Temperature]] and [[humidity]] are the parameters that are typically used to characterize them. They can be warm or cold, dry or humid.

His main interest was in [[atom]]ic and molecular structure, especially the forces between atomic particles, the nature of [[chemical bond]]s 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, [[Charles Coulson|C.A. Coulson]], [[Paul Dirac|P. Dirac]] (1933 Nobel Laureate who came with Jones from Bristol), [[George Garfield Hall|G.G. Hall]], A. Hurley, and [[John Pople|J. Pople]].

An air mass develops over an area where the weather changes little and lends the developing air mass its characteristics. For example, stationary air over the [[Gulf of Mexico]] becomes very warm and humid and then advances northward as a warm moist air mass.

[[Atom]]s of a [[noble gas]] reach an [[equilibrium]] distance from each other when an attracting [[London forces|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 programming language|Java]] [[Applet]]) honours him, too.

Air masses move from their source regions in response to the flow aloft in the atmosphere. At the earth's surface, a cold front introduces a colder and (usually) drier air mass to a region; a warm front introduces a warmer air mass.

Keele University holds a collection of Lennard-Jones's published work. Professor C.A. Coulson’s 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-Jones’s 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]].<br>

1912 Studied [[mathematics]] as an [[undergraduate]] at the [[University of Manchester]]<br>

1915-18 [[First World War]] service in the [[Royal Flying Corps]]<br>

1919-22 Studies for Doctor of Science degree and lectures in Mathematics at Manchester University. <br>

1922 Receives Doctor of Science degree at Manchester <br>

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.<br>

1924 Receives Doctor of Science degree at Cambridge. Proposes a semi-empirical [[interatomic force]] law.<br>

1925 Marries Kathleen Lennard<br>

1925-32 Professor of Theoretical Physics, [[Bristol University]]<br>

1929 Paper [1] introduces the [[Linear combination of atomic orbitals molecular orbital method|Linear Combination of Atomic Orbitals]] approximation for [[molecular orbitals]]<br>

1929 Brings to Bristol [[Gerhard Herzberg]] (1971 [[Nobel Prize in Chemistry|Nobel Laureate for chemistry]]) to study [[spectroscopy|spectra]] of [[diatomic|di-]] & [[polyatomic ion|poly-]]atomic [[molecules]].<br>

1930-2 Dean of the Faculty of Science, Bristol University<br>

1931 Paper [2] introduces method for the atomic [[Self-consistent field method|Self-Consistent Field]] (SCF) equations. Proposes the [[Lennard-Jones potential]]<br>

1932-53 Plummer Professor of [[theoretical chemistry|Theoretical Science]], [[Cambridge University]]. Founded the theoretical chemistry section of Cambridge University Chemical Laboratory.<br>

1934 Paper [3] applies [[group theory]] to explain energies & structures of [[hydrocarbon]] free radicals<br>

1933 Elected a fellow of the [[Royal Society]]<br>

1934 Graduate student Charles Coulson (in 1972 [[Oxford University]]'s first Professor of Theoretical Chemistry) completes PhD<br>

1937 Paper [4] on conjugated hydrocarbons <br>

1937 First Director of [[University of Cambridge Mathematical Laboratory|Cambridge University Mathematical Laboratory]] (now [[University of Cambridge Computer Laboratory|Cambridge University Computing Laboratory]]) with [[Maurice Wilkes]] as researcher.<br>

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. <br>

1942-5 Director-General of Scientific Research (Defence), Ministry of Supply<br>

1942-7 Member of the Advisory Council of the Department of Scientific and Industrial Research.<br>

1946 Knighted (KBE), returns to Cambridge<br>

1947-53 Chairman of the Scientific Advisory Council at the Ministry of Supply<br>

1948-50 President of the [[Faraday Society]]<br>

1949 Paper [5] justifies use of diatomic [[molecular orbital|orbitals]] only for [[valence]] [[electrons]] by showing the determinantal [[Schrödinger equation|wave function]] to be invariant under unitary transformations that could accurately transform molecular orbitals into localized equivalent orbitals.<br>

1950 Paper [6] completely defines molecular orbitals as [[eigenfunction]]s of the SCF [[Hamiltonian]]<br>

1951 Graduate student [[John Pople]] (1998 [[Nobel Prize in Chemistry|Nobel Laureate for chemistry]]) completes PhD <br>

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<br>

1953 Succeeds [[Alexander Lindsay]] as 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.<br>

1954 Honorary doctorate of science, [[Oxford University]]; dies aged 60.<br>

== Papers ==

1. Lennard-Jones, J.E. (1929) Trans.Faraday Soc. 25, 668.<br>

2. Lennard-Jones, J.E. (1931) Proc.Camb.Phil.Soc. 27, 469.<br>

3. Lennard-Jones, J.E. (1934) Trans.Faraday Soc. 30, 70.<br>

4. Lennard-Jones, J.E. (1937) Proc.Roy.Soc. A158, 280.<br>

5. Lennard-Jones, Sir John (1949) Proc.Roy.Soc. A198, 1,14.<br>

6. Hall, G.G. and Lennard-Jones, Sir John (1950) Proc.Roy.Soc. A202, 155.<br>

==External link==

*[http://www.quantum-chemistry-history.com/LeJo_Dat/LJ-Hall1.htm ''The Lennard-Jones paper of 1929 and the foundations of Molecular Orbital Theory'' by George G. Hall]

[[Category:Mathematicians]]