DIRECT DETERMINATION OF LOCALIZED HARTREE-FOCK ORBITALS AS A STEP TOWARD N SCALING PROCEDURES

A method is proposed for the solution of the self-consistent field equ ations that can lead to localized occupied and virtual molecular orbit als, avoiding the need for solving for the canonical molecular orbital s. The method starts with strongly localized ''guess molecular orbital s'', it is nonperturbative and proceeds through the diagonalization of single configuration interaction matrices which may be rendered size- consistent through appropriate coupled electron pair approximation or coupled-cluster-type dressings. We see a potential utility for the met hod in applications to large systems where localized orbitals will imp rove the scaling of the computational resources required with increasi ng system size. (C) 1997 American Institute of Physics. [S0021-9606(97 )00947-1].