Coulson–Fischer theory

In theoretical chemistry and molecular physics, Coulson–Fischer theory provides a quantum mechanical description of the electronic structure of molecules. The 1949 seminal work of Coulson and Fischer^[1] established a theory of molecular electronic structure which combines the strengths of the two rival theories which emerged soon after the advent of quantum chemistry - valence bond theory and molecular orbital theory, whilst avoiding many of their weaknesses. For example, unlike the widely used Hartree–Fock molecular orbital method, Coulson–Fischer theory provides a qualitatively correct description of molecular dissociative processes.^[2] The Coulson–Fischer wave function has been said to provide a third way in quantum chemistry.^[3] Modern valence bond theory is often seen as an extension of the Coulson–Fischer method. For a single two-electron bond, the Coulson–Fischer theory is equivalent to the Generalized valence bond method.

References

1. C.A. Coulson and I. Fischer, Notes on the Molecular Orbital Treatment of the Hydrogen Molecule,Philos. Mag. 40, 386 (1949)
2. S. Wilson and J. Gerratt, Calculation of potential energy curves for the ground state of the hydrogen molecule, Molec. Phys. 30, 777 (1975)
3. S. Wilson, On the Wave Function of Coulson and Fischer: A Third Way in Quantum Chemistry, in Advances in the Theory of Atomic and Molecular Systems, ed. P. Piecuch, J. Maruani, G. Delgado-Barrio and S. Wilson, Progress in Theoretical Chemistry and Physics 19, Springer (2009)