Library

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
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 95 (1991), S. 8726-8731 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 265-269 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: This paper presents state-to-state integral cross sections for the exchange reaction H+H2(0,j=0,2)→H2(1,j'=1,3,5)+H calculated from quasiclassical trajectories (QCT) on the Liu–Siegbahn–Truhlar–Horowitz (LSTH) potential energy surface in the relative energy range 0.4 to 1.2 eV. These are compared to results of exact quantum calculations at relatively low total energy (∼1 eV) [J. Z. H. Zhang and W. H. Miller, Chem. Phys. Lett. 153, 465 (1988)] and to those of the recent experiments of Kliner et al. [J. Chem. Phys. 94, 1069 (1991)]. Cross sections were calculated directly from trajectories starting in the (0,0) and (0,2) states and indirectly, using microscopic reversibility, from trajectories starting in (1,j'). The resulting QCT cross sections are in reasonable agreement with the quantum calculations, the indirect QCT results being the more satisfactory near threshold. The QCT cross sections behave smoothly with energy and, as expected, do not exhibit mild undulating structure such as is seen in the quantum calculations for (0,0)→(1,1); this is a quantum effect. Also included are QCT cross sections at translational energies near 1.28 and 1.90 eV which are relevant to the prompt reaction used in the experiments of Kliner et al. and for which quantum results are unavailable. The quasiclassical result was found to be somewhat higher than the experimental product ratio (1,3)/(1,1).
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 2671-2676 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: State-to-state cross sections for the collision-induced transitions of H+H2 (and isotopic analogs) have often been examined using quasiclassical trajectory calculations. The assignment of quasiclassical trajectory results to final rotational and vibrational states by histogram methods can lead to distributions for endoergic (upward) transitions that are rotationally or vibrationally hot when compared with quantum calculations or with experimental results. This effect is most pronounced near threshold for the transition of interest. Various histogram methods are examined to determine why they can lead to distributions that are hot. The application of detailed balance (microscopic reversibility) to cross sections calculated for the inverse of the endoergic transition results in distributions that are neither rotationally nor vibrationally hot; only those effects that can be attributed to the classical approximation of a quantum process remain.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 21 (1988), S. 1228-1234 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 19 (1986), S. 2459-2461 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 21 (1988), S. 1222-1227 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 666-689 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The interaction potential energy surface (PES) of H4 is of great importance for quantum chemistry as a test case for molecule–molecule interactions. It is also required for a detailed understanding of certain astrophysical processes, namely collisional excitation and dissociation of H2 in molecular clouds, at densities too low to be accessible experimentally. The 6101 ab initio H4 energies reported in 1991 by Boothroyd et al. demonstrated large inaccuracies in analytic H4 surfaces available at that time. Some undesirable features remained in the more accurate H4 surfaces fitted to these energies by Keogh and by Aguado et al., due in part to the relatively sparse coverage of the six-dimensional H4 conformation space afforded by the 6101 ab initio energies. To improve the coverage, 42 079 new ab initio H4 energies were calculated, using Buenker's multiple reference (single and) double excitation configuration interaction program. Here the lowest excited states were computed as well as the ground state, and energies for the original 6101 conformations were recomputed. The ab initio energies have an estimated rms "random" error of ∼0.5 millihartree and a systematic error of ∼1 millihartree (0.6 kcal/mol). A new analytical H4 PES was fitted to these 48 180 ab initio energies (and to an additional 13 367 points generated at large separations), yielding a significant improvement over previous H4 surfaces. This new PES has an rms error of 1.43 millihartree relative to these 48 180 ab initio energies (the fitting procedure used a reduced weight for high energies, yielding a weighted rms error of 1.15 millihartree for these 48 180 ab initio energies). For the 39 064 ab initio energies that lie below twice the H2 dissociation energy, the new PES has an rms error of 0.95 millihartree. These rms errors are comparable to the estimated error in the ab initio energies themselves. The new PES also fits the van der Waals well to an accuracy of about 5%. For relatively compact conformations (energies higher than the H2 dissociation energy), the conical intersection between the ground state and the first excited state is the largest source of error in the analytic surface. The position of this conical intersection forms a somewhat complicated three-dimensional hypersurface in the six-dimensional conformation space of H4. A large portion of the position of the conical intersection has been mapped out, but trying to include the conical intersection explicitly in an analytic surface is beyond the scope of the present paper. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 1036-1038 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 279 (1979), S. 384-387 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] New spectrophotometry of SS433 shows that the variable-wavelength emission features discovered by Margon et al. are due to the simultaneous presence of material having a substantial redshift and a substantial blueshift. A magnetic interpretation for the features is also ruled out by polarimetric ...
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 225 (1970), S. 197-198 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] It is generally agreed that marsupials migrated from North America to South America, where they first appeared in the Palaeocene, and to Western Europe where they are found in Eocene deposits. The dispersal route to Europe is usually thought to be via the Bering Strait and Asia, but two factors ...
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...