Beyond the Molecular Orbital Approach

4 Beyond the Molecular Orbital Approach Introduction.—In principle an exact solution to the non-relativistic Schrodinger equations for a molecule can be achieved by the configuration interaction technique. A complete set of one-electron spin orbitals f i is used to form a complete set of Slater determinants by choosing all possible ordered sets of n elements of the set of 4u s. A linear combination of these determinants is then used  

In practice, of course this equation must be truncated. It is then convenient to describe the expansion as 

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