Multiconfiguration-self-consistent field (MC-SCF) method for excited states

Abstract
A method is derived to calculate the MC-SCF wavefunctions for the various excited states of a given symmetry. The appropriate orthonormality constraints are taken into account in the construction of the generalized Fock operators. A simplification of the two by two rotation method is suggested for deriving the SCF orbitals. The method is applied to the calculation of the wavefunctions for the first three states of the hydrogen molecule with 1Σu + symmetry.