Possible use of genealogical spin-adapted functions in the table-CI method

The use of genealogical spin-adapted functions (SAFs) in the table-CI metho d for the description of electron correlation in molecular electronic struc ture calculations is suggested. It is demonstrated that genealogical functi ons are compatible with the basic idea of a double representation of SAFs. The genealogical SAFs are shown to lead to an upper triangular matrix relat ing spin-projected main determinants and SAFs as opposed to a fully populat ed square matrix. Consequently, a computational efficiency increase of appr oximately a factor of 2 for this stage of the calculation is expected. (C) 2001 John Wiley & Sons, Inc.