# Calculation of Exchange Energies Using Algebraic Perturbation Theory

 Title: Calculation of Exchange Energies Using Algebraic Perturbation Theory Author: Dalgarno, Alexander; Burrows, Brian L.; Cohen, Maurice Note: Order does not necessarily reflect citation order of authors. Citation: Burrows, Brian L., Alexander Dalgarno, and Maurice Cohen. 2010. Calculation of exchange energies using algebraic perturbation theory. Physical Review A 81(4): 042508. Full Text & Related Files: Dalgarno_Calculation.pdf (168.8Kb; PDF) Abstract: An algebraic perturbation theory is presented for efficient calculations of localized states and hence of exchange energies, which are the differences between low-lying states of the valence electron of a molecule, formed by the collision of an ion $$Y^{+}$$ with an atom $$X$$. For the case of a homonuclear molecule these are the gerade and ungerade states and the exchange energy is an exponentially decreasing function of the internuclear distance. For such homonuclear systems the theory is used in conjunction with the Herring-Holstein technique to give accurate exchange energies for a range of intermolecular separations $$R$$. Since the perturbation parameter is essentially 1/$$R$$, this method is suitable for large $$R$$. In particular, exchange energies are calculated for $$X_{2}$$$$^{+}$$ systems, where $$X$$ is H, Li, Na, K, Rb, or Cs. Published Version: doi:10.1103/PhysRevA.81.042508 Terms of Use: This article is made available under the terms and conditions applicable to Other Posted Material, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#LAA Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:5128485

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