with multiple values of the parameter λ, where F and K are the Fock and exchange matrices generated from the HF density matrix. The operator is diagonalized within the space of all virtual orbitals. Once these virtual orbitals have been generated, the manifold of doubly occupied orbitals i and virtual orbitals a remains unchanged; the next steps serve to select 40 active orbitals and a set of inactive orbitals from this initial manifold.