title: Harmonic electron correlation operator.
abstract: An appealing way to model electron correlation within the single determinant wave function formalism is through the expectation value of a linear two-electron operator. For practical reasons, it is desirable for such an operator to be universal, i.e., not depend on the positions and types of nuclei in a molecule. We show how a perturbation theory applied to a hookium atom provides for a particular form of a correlation operator, hence called the harmonic correlation operator. The correlation operator approach is compared and contrasted to the traditional ways to describe electron correlation. To investigate the two-electron approximation of this operator, we apply it to many-electron hookium systems. To investigate the harmonic approximation, we apply it to the small atomic systems. Directions of future research are also discussed.
authors.affiliation: Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA. rassolov@mail.chem.sc.edu
authors.forename: Vitaly A
authors.initials: VA
authors.lastname: Rassolov