A method of performing ab initio calculations of the electronic struct
ure of fragments within a larger molecule is reported. The method uses
the self-consistent group formalism of McWeeny together with the syst
ematic use of a hybrid atomic orbital basis. The mutual compatibility
of these two ideas is stressed and results are given for model calcula
tions on fragments in saturated hydrocarbon chains and rings. (C) 1996
John Wiley & Sons, Inc.