ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
Filter
  • Articles  (6)
  • Articles: DFG German National Licenses  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Including dispersion in configuration interaction-singles calculations for the spectroscopy of chromophores in solution (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 7293-7299 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper we prove that a configuration interaction electronic structure calculation on a supermolecule that contains only single excitations includes dispersion interactions between the two subsystems when energy differences are taken between the Hartree–Fock (molecular orbital) ground state and low energy excited states in which single excitations dominate. This theorem is proven up to second order in perturbation theory. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481332
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Solvent effects in emission spectroscopy: A Monte Carlo quantum mechanics study of the n←π* shift of formaldehyde in water (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 9132-9139 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Supermolecular calculations that treat both the solute and the solvent quantum-mechanically are performed to analyze the solvatochromism of the first emission transition of formaldehyde in water. The liquid structures are generated by NVT Metropolis Monte Carlo simulation assuming a fully relaxed excited state. The autocorrelation function is calculated to obtain an efficient ensemble average. A detailed analysis of the hydrogen bonds and their contribution to the solvation shift is presented. On average, 0.7 hydrogen bonds are formed in the excited state, about three times less than in the ground state. Quantum-mechanical calculations using the intermediate neglect of differential overlap with singly excited configuration interaction (INDO/CIS) are then performed in the supermolecular clusters corresponding to the hydrogen bond shell and the first, second, and third solvation shells. The third solvation shell extends up to 10 Å from the center of mass of formaldehyde, showing the very long-range effects on the solvation shift of this polar molecule. The largest cluster includes one formaldehyde and 142 water molecules. INDO/CIS calculations are performed on this cluster with a properly antisymmetric reference ground state wave function involving all valence electrons. The estimated limit value for the solvatochromic shift of the n-π* emission transition of fully relaxed formaldehyde in water, compared to the gas phase, is (approximate)1650 cm−1. The total Stokes shift of formaldehyde in water is calculated as (approximate)550 cm−1. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1320827
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    A Monte Carlo-quantum mechanics study of the solvatochromic shifts of the lowest transition of benzene (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 9874-9880 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We examine the spectroscopic red shifts that occur when benzene is dissolved in (liquid) benzene, in cyclohexane, in carbon tetrachloride, and in water. For this we develop a mixed classical/quantum model in which uncorrelated structures are obtained from Monte Carlo simulation, and these structures are then used for quantum chemical calculations including the chromophore and all solvent molecules within the first radial distribution maxima. We discuss the effects of different sampling techniques and the inclusion of more, or less, solvent molecules in the quantum chemical supermolecule calculation. We obtain shifts of −306 cm−1, −268 cm−1, −456 cm−1, and −122 cm−1, in excellent agreement with the experimentally observed shifts of −332 cm−1, −308 cm−1, −458 cm−1, and −143 cm−1, respectively. We note that the larger shift observed in carbon tetrachloride that is not expected on the basis of larger dielectric constant results from small contributions of the charge transfer type from solvent to solute. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481624
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Dynamical scaling in fragmentation (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 7577-7587 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dynamics of a fragmentation model is examined from the point of view of numerical simulation and rate equations. The model includes effects of temperature. The number n(s,t) of fragments of size s at time t is obtained and is found to obey the scaling form n(s,t)∼ s−τtwsγe−ρtf(s/tz) where f(x) is a crossover function satisfying f(x)(approximately-equal-to)1 for x(very-much-less-than)1 and f(x)(very-much-less-than)1 for x(very-much-greater-than)1. The dependence of the critical exponents τ, w, γ, and z on space dimensionality d is studied from d=1 to 5. The result of the dynamics on fractal and nonfractal objects as well as on square and triangular lattices is also examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354984
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Calculation of the absorption spectrum of benzene in condensed phase. A study of the solvent effects (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 65 (1997), S. 885-891 
    Details
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The red shift of the first absorption band of benzene in the condensed phase is calculated. The solid-phase calculations are performed using the experimental crystal structure. For the liquid two different approaches are considered. One is the herringbone structure suggested by X-ray experiments, and the other uses supermolecules generated by Monte Carlo simulation. Attention is given to the contribution of the usual parallel and T-shape conformations of the benzene dimers obtained in the simulation. Comparison with experiment shows a relatively poor result for the herringbone structure and good agreement for the supermolecular structures generated by the simulation.   © 1997 John Wiley & Sons, Inc. Int J Quant Chem 65: 885-891, 1997
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Sampling configurations in Monte Carlo simulations for quantum mechanical studies of solvent effects (1998)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 66 (1998), S. 249-253 
    Details
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Discrete models obtained from computer simulation are in increase use to study solvent effects. The approach consists of generating supermolecular structures for quantum mechanical calculations. The properties of the solute are calculated as an ensemble average over configurations generated by the simulation. An analysis of the efficiency of the simulation shows that the number of configurations necessary for the ensemble average can be reduced drastically. As an application to solvatochromism, the calculated spectral shift of the 1B2u(π - π*) transition of benzene in water is shown to be the same whether it is calculated with many but correlated configurations or with just a few uncorrelated configurations.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 66: 249-253, 1998
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...