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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 3005-3017 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Two degrees of freedom quantum mechanical calculations on the bound states of H+3 are presented. Two different potential energy surfaces are employed. The effect of rotational excitation is analyzed. For J=0, the high energy region is composed largely of states that cannot be assigned. However, two regularly spaced series are observed, corresponding to "horseshoe'' states predicted previously by classical calculations. In addition we find a new assignable series of inverted hyperspherical states. Conversely, for high orbiting angular momentum (l=20) in which the proton rotates about the diatom, assignable normal mode states persist up to dissociation. Semiclassical periodic orbit quantization is found to give excellent agreement for the regular quantum states. The significance of these results for the interpretation of the H+3 photodissociation spectrum is discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 2524-2524 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The neutral–neutral and ion–neutral reactions of Mu, Mu+, HMu, and HMu+ with H, H2, H+2, and H+3 are considered. Vibrational zero-point energy effects make the Mu–H exchange reactions endothermic and suggest that little molecule formation occurs in room temperature Mu–H2 mixtures.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 2178-2184 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The two-dimensional interaction potential of the N+2(X 2Σ+g) –He(X 1S) system has been calculated using highly correlated ab initio MCSCF-CI wave functions for a fixed value of the N+2 bond length (2.110 a0). It is found to have a minimum about 140 cm−1 below the N+2 +He dissociation limit, significantly deeper than the minimum in the neutral system N2–He. This well depth is enough to give rise to a cluster-like, bound structure with a considerable number of vibration–rotation levels in the electronic ground state. The well depth is almost independent of the N2–He angle, which leads to large amplitude bending motions. Rovibrational calculations have been performed on the surface for J=0, 1, and 2. Values for the rotational constant B, the fundamental stretching frequency νs, and its first and second overtones, and the rotational constant Cn in each nνs manifold, have been obtained from the energy levels computed. It is found that B=1.879 cm−1, 1νs =55.231 cm−1, 2νs =83.404 cm−1, 3νs =92.491 cm−1, C0=0.477 cm−1, C1=0.370 cm−1, and C2=0.254 cm−1. Estimates of the accuracy of these parameters are made.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 6648-6652 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Variational bound state nuclear motion calculations are performed on a fitted [Joseph and Sathyamurthy, J. Chem. Phys. 86, 704 (1987)] ab initio surface for HeH+2. The linear 4HeH+2 molecule is predicted to have an He–H+2 stretch fundamental of 732 cm−1 with the first J=0 excited bend at 960 cm−1. This isotopomer has no bound excited states of the H+2 vibrational mode. Calculations with J=1 and J=2 predict a rotational constant of 4.0 cm−1 for this system. Results are also presented for all the isotopomers containing D and 3He. The spectrum of this molecule is a good candidate for laboratory or astrophysical observation.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 3377-3386 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A study of the bound states of the H+3 molecular ion at zero total angular momentum is presented. Wave functions are shown for the accurate ab initio Meyer–Botschwina–Burton potential energy surface and the more approximate diatomics in molecules (DIM) surface. The qualitative behavior is similar for the two potentials. The analytic form of the DIM surface enables a study that reaches energies as high as the dissociation threshold. Quantum states are found to localize regularly around the horseshoe periodic orbits found in previous classical studies. There is good agreement between a semiclassical periodic orbit quantization formula and the exact quantum energies. The antisymmetric stretch frequency with respect to the orbit is estimated classically and quantum mechanically and found to be in agreement with a previous estimate. A three-dimensional stability analysis of the horseshoe orbit is presented and used as a basis for the semiclassical theory. The implications on the assignment of the coarse grained photodissociation spectrum measured by Carrington and Kennedy are discussed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 3815-3825 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A formulation of the rovibrational problem in Jacobi coordinates is presented which employs a discrete variable representation for the angular internal coordinate. Rotational excitation is implemented via a two-step procedure and symmetry (for AB2 systems) included using a computationally efficient method. Energies for the lowest 180 vibrational states of H+3 are presented and their wavefunctions analyzed graphically. J=1←0 excitation energies are presented for the lowest 41 vibrational states. The significance of the regular states in the high-energy regime of H+3 is discussed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 9766-9771 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The partition function, Q, of H2〈sup ARRANGE="STAGGER"〉16O is calculated by explicit summation of about 10 500 experimental vibration-rotation energy levels and very high accuracy estimates are obtained for the specific heat capacity (Cp), the Gibbs enthalpy function (gef), the Helmholtz function (hcf) and the entropy (S) of gas phase water as a function of temperature. For temperatures above 600 K it is necessary to augment the sum with theoretical estimates of the energy levels. These are obtained from high accuracy variational calculations which are extended to dissociation using a model for rotational levels based on a Padé approximant. Estimates for the partition function and other thermodynamic quantities are obtained for temperatures up to 6000 K and temperature dependent error bars presented. All estimates are highly accurate with the exception of Cp for T〉5000 K, for which further work is required. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 2163-2164 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 800-809 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Classical and quantum mechanical calculations on the vibrational motions of LiCN using a realistic potential are presented. These, together with recent results for KCN, are analyzed using indicators that have been proposed for identifying quantum chaos. These are nodal structure, dominant coefficient, overlapping avoided crossings, second differences, and spectral distribution. We find an early onset of chaos in LiCN and KCN with good agreement between the indicators. Localized quasiperiodic trajectories and regular states are found well into the chaotic region for both isomers of LiCN. LiCN is a weakly coupled system in contrast to strongly coupled KCN. The utility of the indicators is discussed in the light of these results. The link between floppy molecules and chaos suggests that floppy systems are suitable for the experimental investigation of vibrational chaos.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 7564-7573 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A method of calculation of rotation–vibration states for a general triatomic that places the body-fixed z axis perpendicular to the plane of the molecule is implemented within a discrete variable representation (DVR) for the vibrational motion. Calculations are presented for water and H3+. For H3+ the new method improves on previous high accuracy ab initio treatments of the rotation–vibration energies of the molecule both in accuracy and the range of rotational states that can be treated. Reliable treatment of quasilinear geometries means that the method is also promising for treating very highly excited states. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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