M. LEWIN
The Multiconfiguration Methods in Quantum Chemistry
(288K, Postscript)

ABSTRACT.  The multiconfiguration methods are the natural generalization of the well-known Hartree-Fock theory for atoms and molecules. 
By a variational method, we prove the existence of a minimum of the energy and of infinitely many solutions of the multiconfiguration equations, a finite number of them being interpreted as excited states of the molecule. 
Our results are valid when the total nuclear charge Z exceeds N-1 (N is the number of electrons) and cover most of the methods used by chemists. 
The saddle points are obtained with a min-max principle; we use a Palais-Smale condition with Morse-type information and a new and simple form of the Euler-Lagrange equations.