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An Examination of Basis Set Superposition Error at the Correlated Level: Illuminating the Role of the Exchange
1Department of Chemistry and Physics, University of New England, 11 Hills Beach Road, Biddeford, Maine 04005.
Abstract:
A reformulated 'virtuals-only' counterpoise procedure for the correction of basis set superposition error is introduced and applied to an examination of the interaction energy of the helium dimer. This method allows a direct calculation of the exchange (Pauli) repulsion at the correlated level. Our findings suggest that at the correlated level the Pauli repulsion may be interpreted as a decrease in the monomer correlation energy calculated using the dimer virtual space relative to that with a monomer-only virtual space. This observation provides further theoretical justification for the Full Counterpoise procedure in preference to any virtuals-only counterpoise procedure.
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