On a general system-partitioning in the many-electron correlation problem

General system partitioning in the many-electron correlation problem for atomic and molecular systems is addressed within the spinshift formalism. The conventional method of the unitary group subduction coefficient expansion is reconsidered in the latter framework and an orbital-level factorization of the coefficients is obtained. ''Group-spinshifts'' are introduced and exploited to propose an alternative method of generating states adapted to arbitrary subduction chains. (C) 1996 John Wiley & Sons, Inc.