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
    Optimal generalized internal vibrational coordinates and potential energy surface for the ground electronic state of SO2 (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 139-148 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An optimization of generalized internal vibrational coordinates for the electronic ground state of the SO2 molecule is carried out. These coordinates are given by the magnitudes and the angle formed by two vectors expressed as linear combinations of the internal valence vectors, and depend on two external parameters which can be optimized so as to reduce the vibrational coupling of the molecule as much as possible. The optimal values of the parameters are found by minimizing a set of unconverged vibrational energies which are computed variationally using a small basis function set. It is shown that the optimal internal coordinates obtained for SO2 are superior to both valence and Radau coordinates, as well as to a set of normal coordinates previously derived by proper rotation of the Jacobi S–O2 coordinates. These optimal internal coordinates are then applied to calculate the vibrational energies of the molecule using an ab initio force field expressed as a Morse-cosine expansion, and then to refine it by nonlinear least-squares fitting to the observed vibrational frequencies. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1377893
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    A theoretical study of the vibrational spectrum of the CS2 molecule (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 7495-7508 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A theoretical study of the vibrational spectrum of the CS2 molecule is carried out. For that purpose, a new Morse-cosine potential energy function is determined by fitting to observed vibrational frequencies, using as a starting point an ab initio force field. Highly excited vibrational states for CS2 are then calculated up to 20 000 cm−1 using a DVR truncation-diagonalization method. Hyperspherical Radau coordinates, which are a set of normal curvilinear coordinates for linear symmetric triatomic molecules, are used in these calculations. The computed vibrational energy levels are shown to present an excellent agreement with the observed values up to 13 000 cm−1. Based on these calculations, some unassigned observed vibrational frequencies are identified and the assignments of others are reconsidered. Inspection is made of the vibrational wave functions computed for CS2 revealing a persistent regularity up to 13 000 cm−1. This regularity is found to be consistent with perturbation theory results for these energies. Van Vleck perturbation theory is used to derive effective Hamiltonians that contain polyad quantum numbers and that provide good agreement with the variational calculations. It is also shown that the asymmetric stretch is practically decoupled from the symmetric stretch and the bend in this range of energies. The nearest neighbor space distribution (NNSD) and the Δ3 spectral rigidity function show that the calculated vibrational spectrum of CS2 up to 20 000 cm−1 is essentially regular, in agreement with the most recent statistical analyses made of the spectroscopically observed frequencies.© 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1465413
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Excited vibrational states and potential energy function for OCS determined using generalized internal coordinates (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 5695-5704 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Variational calculations of excited vibrational states for the OCS molecule, using generalized internal coordinates properly optimized, are presented. The calculations are made for two empirical and one ab initio potential energy surfaces previously reported. It is shown that the computed vibrational frequencies differ considerably from the experimental values for the three potential surfaces employed. Consequently a new and much more accurate potential surface is determined for OCS by nonlinear least-squares fitting to the observed vibrational terms. The surface is expressed as a Morse-cosine expansion in valence coordinates and its quality is checked by computing the vibrational frequencies of three isotopic species of the molecule. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1290383
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulation of the I2(X)(centered ellipsis)Ar isomers population in a free-jet expansion: Thermodynamics versus kinetic control (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 1944-1953 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A molecular dynamics simulation addressing the problem of thermodynamic versus kinetic control of the isomers population of van der Waals complexes in a supersonic expansion is presented. The populations of the linear and T-shaped isomers of I2(X)(centered ellipsis)Ar in a supersonic beam expansion were determined by molecular dynamics simulation as a function of the distance to the nozzle and compared to the prediction of thermodynamics. The surprising conclusion is that although there is a barrier equal to half the well depth between the two isomers, their populations are consistent with the existence of thermodynamic equilibrium. This result is rationalized by examining the cooling mechanisms in the Ar+I2(X)(centered ellipsis)Ar collisions. In addition to the direct isomerization, a new mechanism (swap cooling), which induces isomerization even for complexes with barriers above the dissociation limit, is evidenced. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1431275
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Erratum: "Time evolution of reactants, intermediates and products in the vibrational predissociation of Br2⋅⋅⋅Ne: A theoretical study" [J. Chem. Phys. 113, 10130 (2000)] (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 7713-7713 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The lower part of Fig. 6 was erroneous, due to a transcription error. The MDQT and experimental results now show a much better agreement with the quantum mechanical ones for the Δv=−2 channel of the Br2⋅⋅⋅Ne(v=27) vibrational predissociation, as was the case for the other channels and the other initial vibrational levels. The rest of the paper is unchanged. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1361066
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Time evolution of reactants, intermediates, and products in the vibrational predissociation of Br2(centered ellipsis)Ne: A theoretical study (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 10130-10142 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A hybrid quantum/classical simulation of the vibrational predissociation of the Br2(centered ellipsis)Ne cluster in the B state is carried out. The resulting lifetimes and final rovibrational state distributions compare very well with the experimental measurements, as well as with accurate quantum mechanical results. The time-evolution of the reactants, products, and intermediates is analyzed by a kinetic mechanism, comporting three elementary steps: direct vibrational predissociation (VP), intramolecular vibrational redistribution (IVR), and evaporative cooling (EC). The importance of intramolecular vibrational redistribution followed by evaporative cooling relative to direct vibrational predissociation is shown to evolve from 100% of VP for the lowest initial vibrational level v=10 to 53% for the highest one v=27. In the cases where IVR is important, the complexes are shown to explore the whole configuration space, in contrast with the cases where dynamics are governed by direct vibrational predissociation for which the complexes mainly evolve in the region around the T-shaped equilibrium configuration. A time-dependent picosecond experiment is proposed to detect the IVR intermediates, based on their different structure. It consists of exciting the complex with a first laser and probing the intermediates with a second laser to an electronic state with a minimum in the collinear configuration where the initially excited state wave function has no weight. The ground state of the positive ion is proposed as the final state, so that ions are detected. An appreciable population of intermediates is predicted for initial excited levels with v≥20. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1323506
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Hybrid quantum/classical simulation and kinetic study of the vibrational predissociation of Cl2(centered ellipsis)Nen (n=2, 3) (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 4577-4588 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A hybrid quantum/classical method is applied to the vibrational predissociation of van der Waals clusters containing a diatomic molecule and several rare gas atoms, Cl2(centered ellipsis)Nen (n=2, 3). The vibrational degree of freedom of the diatomic is treated quantum mechanically while all the other degrees of freedom are treated classically. A kinetic mechanism is proposed in order to interpret the dynamics in terms of the following elementary steps; vibrational predissociation (VP), intramolecular vibrational redistribution (IVR), and evaporative cooling (EC). The resulting lifetimes are in very good agreement with the experimental linewidth measurements of Janda and co-workers, and with the quantum mechanical reduced-dimension results of Le Quéré and Gray on Cl2(centered ellipsis)Ne2. The final rotational state distributions agree very well with the experimental results and exhibit a quasistatistical behavior. The final vibrational distributions reproduce the main experimental features. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479219
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Hyperspherical Kinematic Vibrational Coordinates for Linear Triatomic Molecules (1995)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 11051-11060 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100028a003
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Self-consistent-field calculation of vibrational bound states for triatomic molecules using transformed Jacobi coordinates (1991)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 95 (1991), S. 2292-2297 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100159a035
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Determination of highly excited rovibrational states for N2O using generalized internal coordinates (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 6339-6352 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Generalized internal vibrational coordinates are optimized and used to describe highly excited vibrational motions in the N2O molecule. These coordinates are defined as the magnitudes of two vectors, which are expressed as linear combinations of the internal displacement vectors and the angle formed between them. They depend on two parameters and contain, as particular cases, valence and orthogonal (Jacobi, Radau, etc.) coordinate systems. The coordinates are optimized by minimizing unconverged variationally computed vibrational energies with respect to the external parameters. A comparison of the optimal internal coordinates derived for N2O with valence and hyperspherical normal coordinates is made. The optimal internal coordinates are also used to determine a new potential energy function for N2O from the observed vibrational frequencies up to 15 000 cm−1 using fully variational calculations. The quality of the adjusted potential energy function is checked by computing vibrational-rotation energy levels and rotational constants for Σ, Π, Δ, Φ, and Γ states and comparing them with the observed values. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478538
    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...