Electronic Resource
College Park, Md.
:
American Institute of Physics (AIP)
The Journal of Chemical Physics
112 (2000), S. 9711-9715
ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The Hartree–Fock self-consistent-field approximation has provided an invaluable conceptual framework and a standard computational procedure for atomic and molecular quantum theory. Its shortcomings are significant however, and require remediation. Møller–Plesset perturbation theory offers a popular correction strategy: it formally expands eigenfunctions and eigenvalues as power series in a coupling parameter λ that switches the Hamiltonian continuously between the Hartree–Fock form (λ=0) and the electron-correlating "physical" Hamiltonian (λ=1). Recent high-order Møller–Plesset numerical expansions indicate that the series can either converge or diverge at λ=1 depending on the chemical system under study. The present paper suggests at least for atoms that series convergence is controlled by the position of a singularity on the negative real λ axis that arises from a collective all-electron dissociation phenomenon. Nonlinear variational calculations for the two-electron-atom ground state illustrate this proposition, and show that series convergence depends strongly on oxidation state (least favorable for anions, better for neutrals, better yet for cations). © 2000 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.481608
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