Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Geometry of intersecting potential surfaces (1974)
    s.l. : American Chemical Society
    Accounts of chemical research 7 (1974), S. 20-25 
    Details
    ISSN: 1520-4898
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ar50073a004
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Iodine Inhibition in the Flash Photolysis of Methyl Iodide (1952)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 74 (1952), S. 6277-6279 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01144a507
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    An ab initio semirigid bender calculation of the rotation and trans-tunneling spectra of (HF)2 and (DF)2 (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 5154-5159 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Using a purely ab initio minimum energy path for the trans-tunneling motion in the HF dimer, the energy levels for the K-type rotation and trans-tunneling motion for (HF)2 and (DF)2 are calculated with a one-dimensional semirigid bender Hamiltonian and no adjustable parameters. The transition moments for rotation-tunneling transitions are calculated, using our ab initio value for the dipole moment of an isolated HF molecule, and we also calculate B¯ values. The energy levels we obtain are in close agreement with experiment; for example, the K=0 tunneling splitting in (HF)2 is calculated as 0.65 cm−1 compared to the experimental value of 0.658 69 cm−1. As well as showing that our ab initio minimum energy path is very good, the calculation demonstrates that the semirigid bender formalism is able to account quantitatively for the unusual K dependence of the rotational energies resulting from the quasilinear behavior, and that the trans-tunneling motion is separable from the other degrees of freedom. We use the results to predict the locations, and transition moments, of the ΔK=0 and ±1 subbands in the tunneling spectra of (HF)2 and (DF)2, many of which have not yet been observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457613
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Fermi resonances and local modes in water, hydrogen sulfide, and hydrogen selenide (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 4171-4185 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A simple vibrational curvilinear internal coordinate Hamiltonian for bent H2X molecules is constracted by expanding the g matrix elements and the potential energy function in terms of the Morse variable y=1−exp(−ar) and retaining important local mode and Fermi resonance terms. The eigenvalues of this Hamiltonian are calculated variationally using Morse oscillator basis functions for the stretches and harmonic oscillator basis functions for the bend. The nonlinear least-squares method is used to optimize the potential energy parameters. The model is applied to water, hydrogen sulfide, and hydrogen selenide. Experimental vibrational levels up to 18 500 cm−1 for five symmetrical isotopic species of water are reproduced with a standard deviation of about 4 cm−1. For both hydrogen sulfide and hydrogen selenide two symmetrical isotopic species were included in the optimization procedure and standard deviations of 1.0 and 0.66 cm−1 were obtained. The potential energy parameters obtained agree well with previous anharmonic force field calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453824
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Adiabatic approach to the coupling between local- and normal-like modes (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 2207-2223 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An adiabatic method of incorporating harmonic bending and stretching modes into the local mode model is developed. This is achieved by defining local normal mode coordinates which enable one to treat some of the stretches as local modes and the other vibrational degrees of freedom as normal modes in a perfectly systematic fashion. An energy level expression for a system of local modes coupled to local normal modes (harmonic oscillators) is derived. The expression has the same form as the standard normal mode formula. A simple formula for the anharmonicity constant xbs is obtained. The formulas are shown to reproduce well the experimental results for H2O, H2S, and H2Se and are tested against previous calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452119
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Quantum canonical transformation of the rotational–vibrational Hamiltonian to remove a Coriolis term (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 461-477 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A quantum mechanical rotational–vibrational Hamiltonian with one Coriolis term which couples vibration and rotation is transformed to eliminate the Coriolis term. This is achieved by employing a Bogoliubov–Tyablikov transformation. A closed-form energy level expression is obtained for the vibrational–rotational energy levels of a rigid symmetric top coupled to harmonic oscillators. For an asymmetric rotor the transformation introduces small off-diagonal matrix elements which couple vibrational states. Nearly degenerate vibrational states would be strongly coupled by the original Coriolis term, but the small off-diagonal matrix elements of the transformed Hamiltonian may be treated perturbatively to obtain an effective rotational Hamiltonian for each vibrational state. The new theoretical method is compared with variational calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460362
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    State-to-state and total rotational energy transfer rate constants for CN(B 2Σ+,v=0,N)+H2, CN(X 2Σ+,v=2,N)+H2, D2, and CN(X 2Σ+,v=3,N)+NO (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 3617-3625 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: State-to-state and total rotational energy transfer (RET) rate constants were measured for collisions of CN(B 2Σ+,v=0,Ni=4,7,8,11) with H2, CN(X 2Σ+,v=2,Ni=4,11) with H2 and D2, and CN(X 2Σ+,v=3,Ni=4) with NO at room temperature and under single, or near-single, collision conditions. Rate constants were also measured for electronic quenching of CN(B 2Σ+,v=0,Ni=4,7,8,and 11) by H2. In general, state-to-state RET rate constants showed very small or no even–odd alternations as the final rotational state varied. Total rate constants for CN(X 2Σ+,v=2,N)/H2, D2 were found to decrease with increasing rotational quantum number, N. By contrast, total rate constants for CN(B 2Σ+,v=0,N)/H2 were found to be relatively independent of N. Exponential energy gap and angular momentum fitting functions were found to represent measured state-to-state RET rate constants very well and were substantially equally effective in this regard. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1446033
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    The advantage of writing kinetic energy operators in polyspherical curvilinear coordinates in terms of zi=cos φi (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 4413-4414 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: It is straightforward to use kinetic energy operators (KEOs) written in polyspherical coordinates without computing an extra potential-like term, frequently called, V′, or a vector of coefficients multiplying terms with first derivatives with respect to the coordinates. The general polyspherical KEO can be written so that it does not involve gφ, where g=Πn=1Nmn3grgφ. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480987
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Accelerating the calculation of energy levels and wave functions using an efficient preconditioner with the inexact spectral transform method (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 9254-9264 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In an earlier paper [J. Chem. Phys. 112, 8765 (2000)] our group introduced a preconditioned inexact spectral transform method for calculating energy levels and wave functions. Although we could calculate high-lying levels with far fewer matrix–vector products than with the filter diagonalization method of Mandelshtam and Taylor, even better performance can be achieved with a better preconditioner. In this paper, we develop an extremely efficient preconditioner consisting of two components: (1) transformation to an optimal separable basis, in which off-diagonal elements of the Hamiltonian matrix are minimized; and (2) removal of all off-diagonal coupling near the energies of interest. The new preconditioner works extremely well; it enables us to calculate high-lying vibrational states of H2O with orders of magnitude fewer matrix–vector products than for all other known methods. The new preconditioner should also accelerate the calculation of other quantities, such as photodissociation cross sections and rate constants. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1367396
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    A new iterative method for calculating energy levels and wave functions (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 8765-8771 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present an efficient iterative method for calculating energy levels and wave functions. The method requires storing only a small number of vectors but allows one to calculate energy levels and wave functions with far fewer matrix–vector products than the filter diagonalization method of Mandelshtam and Taylor. A zeroth-order Hamiltonian is used to precondition a spectral transform Lanczos method. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481492
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...