Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Theoretical and Physical
A Non-Born–Oppenheimer Effective Hamiltonian for the Analysis of Vibrational–Rotational and Rotational Spectra of Diatomic Molecules
Hiromichi Uehara
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2004 Volume 77 Issue 12 Pages 2189-2191


A non-Born–Oppenheimer effective Hamiltonian for diatomic molecules with optimal fitting parameters, i.e., determinable clusters of expansion coefficients of Born–Oppenheimer corrections, has been derived. The effective Hamiltonian has formally the same form as Dunham’s Hamiltonian, except for additional corrections for successive ξ′i terms of a series expansion of the rotational parameter B(ξ′), extending the determinacy of the optimal parameters, ΔBa,b, Δωa,b, Δaiqa,b, riqa,b, in general for i = 1, 2, 3, ..., if spectra of isotopomers of atoms A and B are analyzed simultaneously. The effective Hamiltonian provides a clear-cut understanding of determinable correction parameters; e.g., in Dunham-type potential fits to spectral transitions for the single isotopomer optimal parameters δriq (i = 1, 2, ...) for corrections of series expansion terms of B(ξ′) should explicitly be included. The physical significance of the optimal parameters as well as of conventional molecular parameters, Be, −De, He, ωe, and −αe, etc., is described.

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© 2004 The Chemical Society of Japan
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