Basis-independent potential energy curves for the neutral diatomics of Li,Na and K evaluated by means of Hartree-Fock and different density functional potentials |
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Authors: | Dirk Heinemann Arne Rosén |
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Institution: | (1) Department of Physics, Chalmers University of Technology and University of Göteborg, S-412 96 Göteborg, Sweden;(2) Department of Physics, University of Kassel, W-3500 Kassel, Germany |
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Abstract: | Summary The solution of the Schrödinger equation for diatomic molecules when the finite element method is used gives the possibility to evaluate highly accurate basis-independent potential energy curves. In this work such types of numerically accurate potential energy curves on the HF level have been evaluated for Li2, Na2 and K2 and could be used as benchmarks in the optimization of basis sets. A comparison between recent LCAO HF calculations in which extended basis sets are used and the accurate values determined in this work show that there is a difference in total energy of 4×10–5 and 10–3 a.u. for Li, Li2, and Na, Na2, respectively. Evaluated dissociation energies are, however, due to the cancellation of numerical errors in much better agreement. Further, it is found that different exchange correlation potentials for the heavier molecules such as those given by von Barth-Hedin and Vosko, Wilk and Nusair reproduce experimental properties such as dissociation energies, vibrational frequencies almost as well as those achieved with advanced CI methods. TheX potential gives accurate bond lengths for Na2 and K2, whereas the dissociation energies are too small. |
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Keywords: | Neutral diatomics Basis-independent potential energy curves Li2 Na2 K2 |
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