Doubly-occupied orbital MCSCF methods

A new computational method for a previously suggested Multi-Configuration SCF molecular wave function is developed and applied to some simple molecules. The method involves the use of a single Fock-like hamiltonian matrix for all the MCSCF orbitals and does not involve orthogonality constraints or coupling operators. Application to lithium hydride shows that this method is capable of recovering a large part of the correlation energy and compares very favourably with conventional lengthy CI methods.