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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. April 2005, Volume 4, Number 4, 279-308 |
Avoided Curves Crossings of the Rydberg
[(AHa+)(e-)Rydberg] (a = 2-4)
Radical
Jong Keun Park
Internet Electron. J. Mol. Des. 2005, 4, 279-308
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Abstract:
Potential energy curves of the ground and low lying excited states
for the dissociation of the Rydberg AHa (NH4, H3O,
H2F; 11
electron species) radical into [AHb + Hc; b = 1-3, c=1-2, b+c = a]
have been calculated using ab initio Hartree-Fock (HF) and singly
and doubly excited configuration interaction (SDCI) methods with
a large basis set including Rydberg basis functions. In the ground
and excited correlation curves, the potential curves of the
[(AHa+)(e-)Rydberg]
radical diabatically correlate to the [AHb (n→3s,
3p) + Hc] and the [AHb+ + Hc-]
asymptotes. At shorter than R(AH) ≅
2.0 Å, the avoided curve crossings between the dissociative
diabatic states of the
[(AHa+)(e-)Rydberg]
radical and the repulsive
diabatic states emerging from the antibonding interactions of the
[AHb (n→3s, 3p) + Hc] asymptotes are found mainly. While, at
larger than R((AH) ≅ 2.0 Å, the avoided curve crossings between the
attractive diabatic states emerging from a bonding interaction of
the [AHb+ + Hc-]
asymptotes and the repulsive diabatic states from
the antibonding orbitals of its asymptotes are found. A maximum
position of the potential energy barrier of the ground correlation
curve is located out of line of those of the excited states. The
potential energy barriers formed by some avoided curve crossings
are found to be relatively low. The potential wells are shallowly
quasibound. The potential energy gaps between the Rydberg AHa
radical and its dissociation asymptotes are very low. The relative
stabilities of metastable states from NH4 to H2F are decrease
monotonously.
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