Heitler, Walter

Heitler, Walter (1904-81) German-born physicist. Heitler is most famous for a classic paper he wrote with Friz London in 1927 in which they showed that the chemical bond in the hydrogen molecule could be described by quantum mechanics. Heitler extended this work to more complicated molecules and was a pioneer of the use of group theory in quantum mechanics. He wrote a classic book entitled The Quantum Theory of Radiation, the third edition of which was published in 1954. 

The classic HLSP-PP-VB (Heitler-London-Slater-Pauling perfect-pairing valence-bond) formalism and its chemical applications are described by L. Pauling, The Nature of the Chemical Bond. 3rd edn. (Ithaca, NY, Cornell University Press, 1960 G. W. Wheland, The Theory of Resonance (New York, John Wiley, 1944) and H. Eyring, J. Walter, and G. E. Kimball, Quantum Chemistry (New York, John Wiley, 1944). 

Walter Heitler s and Fritz London s demonstration (1927) that the source of strength of the covalent bond lies in quantal resonance or the tendency of electrons to maximize their freedom from excessive localization. 

Even worse, Pauling found out in Zurich that he would not be the first to apply wave mechanics to the chemical bond. Two young German acquaintances of his, Walter Heitler and Fritz London, had beaten him to it. Working closely with Schrodinger, they had found a way to use the wave equation to create a mathematical model of a simple chemical bond. 

The first electronic function to be defined in direct association with a formal chemical bond was, as expected, for the H2 molecule. It marked the beginning of the so called valence-bond theory, in 1927, and was suggested by the Austrian physicist Walter H. Heitler (1904—1981) and by the German physicist Fritz W. London (1900-1964). 

The application of Walter Heitler and Fritz London s valence bond theory was the first description of the binding forces in the H2 molecule, the simplest neutral molecule. Linus Pauling and John Slater later extended the principles to larger molecules.The key element in their proposal was the synthesis of a bonding wavefunction resulting from a combination of atomic orbitals that link the two atoms in a bond. It was hugely important that this localized approach concurred with the Lewis dot model. For the simplest neutral molecule, H2, the Hamiltonian operator may be written... 

Walter Heitler and Fritz Wolfgang London convincingly explained why two neutral atoms (like hydrogen) attract each other with a force so strong as to be comparable to the Coulomb forces between ions. Applying the Pauli exclusion principle when solving the Schrddinger equation is of key importance. Their paper was received on June 30,1927, by Zeitschrift fur Physik, and this may be eounted as the birth date of quantum chemistry. ... 

Walter Heitler (1904- 1981) was a German chranist and professor at the University in Gottingen, and later he worked in Bristol and Zurich. 

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