Heitler-Pauling bonding model

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 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... 

Only the first of these truly originates from him. In the first paper of the series, Pauling took up the idea of spatially directed bonds. By a generalization of the Heitler-London model for hydrogen, a normal chemical bond can be associated with the spin pairing of two electrons, one from each of the two atoms. While an s orbital is spherically symmetrical, other atomic... 

Their results provided quantum-mechanical backing for the Lewis shared-electron-pair model for the chemical bond. As noted in two more landmark articles published by Pauling [60] and Slater [61] in 1931, the calculations of Heitler and London also suggested that the chemical bond will be strongest if the two atomic... 

The Heitler-London papers mark the birth of VB theory [2], which was developed by Pauling as a quantum mechanical version of the Lewis model. This quantum mechanical articulation of Lewis shared-pair model has culminated in a generalizing intellectual constmct [25], which described the electron-pair bond A-X as a superposition of covalent (cov) and ionic forms, a+x— and 4>a—x+ [Eq. (2a) and (2b)]. 

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