dc.creator Das, G. en_US dc.creator Wahl, Arnold C. en_US dc.date.accessioned 2006-06-15T13:49:15Z dc.date.available 2006-06-15T13:49:15Z dc.date.issued 1976 en_US dc.identifier 1976-TB-11 en_US dc.identifier.uri http://hdl.handle.net/1811/9816 dc.description Author Institution: Chemistry Division, Argonne National Laboratory en_US dc.description.abstract An ab initio theory is presented that enables one to treat a polyatomic system by breaking it up into molecular fragments based on chemical intuition and carry out calculations on one of these fragments at a time. Unlike the Molecular-Fragment method of Christoffersen et al.,$^{1}$ the present method fragments even the SCF or MCSCP computations In the sense that in a given step one optimizes the orbitals for one molecular fragment only, with the rest of the polyatomic system serving as an environment. The greatest advantage of such an approach lies in the fact that since the orbitals belong to one or the other of the fragments, they are represented by basis functions which are centered on that particular fragment or its nearest neighbors. Thus, the number of integrals to be computed as well as the efforts needed for SCF-optimizations are drastically reduced. Expressions for the total energy, the orbital energies, and the formulae relating to the orbital optimizations are derived. The correlation problem under the present scheme is discussed. The method is illustrated by actual computation on the ethylene molecule. en_US dc.format.extent 150866 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title AN AB-INITIO MOLECULAR-FRAGMENT APPROACH TO LARGE POLYATOMIC MOLECULAR SYSTEMS en_US dc.type article en_US
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