Hydrogen molecule, Heitler-London treatment

One widely used valence bond theory is the generalised valence bond (GVB) method of Goddard and co-workers [Bobrowicz and Goddard 1977]. In the simple Heitler-London treatment of the hydrogen molecule the two orbitals are the non-orthogonal atomic orbitals on the two hydrogen atoms. In the GVB theory the analogous wavefunction is written ... 

Coulson described the first ten years of quantum chemists work on the electron valence bond (roughly 19281938) as work spent "escaping from the thought-forms of the physicist [my emphasis], so that the chemical notions of directional bonding and localization could be developed."45 Heisenberg earlier claimed that the Heitler-London treatment of the hydrogen molecule was not a characteristically physical approach, in contrast to Hund s more "general"... 

The second method of discussing the electronic structure of molecules, usually called the valence-bond method, involves the use of a wave function of such a nature that the two electrons of the electron-pair bond between, two atoms tend to remain on the two different atoms. The prototype of this method is the Heitler-London treatment of the hydrogen a olecule, which we shall now discuss. 

The Heitler-London Treatment of the Hydrogen Molecule.—The hydrogen molecule consists of two nuclei, which may be designated A... 

The origin of the VB model the Heitler-London treatment of the hydrogen molecule... 

It was Pauling and his collaborators who generalized the Heitler-London treatment of the hydrogen molecule to general polyelectronic systems and gave the rules for evaluating the Hamiltonian matrix elements [3,4], which could also... 

The first step in the Heitler-London treatment of the H2 ground state is to approximate the molecule as two ground-state hydrogen atoms. The wave function for two such noninteracting atoms is... 

The original VB wave function was introduced in the treatment of the hydrogen molecule by Heitler and London in 1932. This treatment considered only the one Is orbital on each hydrogen atom and assumed that the best wave function for a system of two electrons on two different atoms is a product of the two atomic Is orbitals i/ — XisXis- This wave function needs to be modified, however, to accommodate the antisymmetry of the wave function and to take into account the spin of the two electrons. 

The most satisfactory treatment which has been given the structure of the hydrogen molecule is that of Heitler and London... 

London (1928) was first to apply this idea to a chemical reaction. London and Heitler developed a simple quantum mechanical treatment of hydrogen molecule, according to which, the allowed energies for H2 molecules are the sum and differences of two integrals as... 

Two sets of papers in 1927 now provided successful treatments of the hydrogen molecule. One was written by Heitler and London, in residence at Schrodinger s institute in Zurich. The other was by Hund, Bom s assistant in... 

The formal results of the quantum-mechanical treatment of valence, developed by Heitler, London, Born, Weyl, Slater, and other investigators, can be given the following simple statement an atom can form an electron-pair bond for each stabh orbital, the bond being of the type described for the hydrogen molecule and owing its stability to the same resonance phenomenon. In other words, for the formation of an eleo-tron-pair bond two electrons with opposed spins and a stable orbital of oach of the two bonded atoms are needed. 

The calculation of Heitler and London (1927) of the energy of the hydrogen molecule must indeed be considered, together with the conception of the spatial model of the carbon atom by Van t Hoff and Le Bel, as the most important contribution to theoretical chemistry, since the advent of Dalton s atomic hypothesis. We shall, however, let the treatment of the hydrogen molecule itself be preceded by the discussion of the hydrogen molecule ion H2+, since this problem with only one electron is still simpler than that of the H2 molecule itself. 

The first quantum-mechanical treatment of the hydrogen molecule was by Heitler and London in 1927. Their ideas have been extended to give a general theory of chemical bonding, known as the valence-bond (VB) theory. The valence-bond method is more closely related to the chemist s idea of molecules as consisting of atoms held together by localized bonds than is the molecular-orbital method. The VB method views molecules as composed of atomic cores (nuclei plus inner-shell electrons) and bonding valence electrons. For H2, both electrons are valence electrons. 

The Heitier-London-Slater-Pauling (HLSP) method. This method, which was developed originally by Slater as a generalization of Heitler and London s treatment of the hydrogen molecule, was... 

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