Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 1
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Signatur 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 93 (1990), S. 8187-8195 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The properties of excess hydrated electrons in liquid water, at room temperature, are studied via coupled quantum-classical simulations. In these simulations, the system evolves dynamically on the adiabatic potential energy surface with the electron maintained in the ground state throughout the process. The diffusion constant of the hydrated electron under field-free conditions is found to be the same as that obtained, via the Nernst–Townsend–Einstein relation, from the electron mobility simulated for a system under an electric field of 3.2×106 V/cm, acting on the electron. For larger electric fields, the electron mobility is found to be field dependent. The mode of migration of the excess electron is polaronic in nature and the influence of the intramolecular degrees of freedom of the water molecules on the hydrated electron transport properties is investigated. It is shown that the electron diffusion constant obtained in simulations under field-free conditions with rigid-water molecules [D0e=(3.7±0.7)×10−5 cm2/s] is larger than that obtained from simulations where a flexible-water model potential is employed D0e=(1.9±0.4)×10−5] cm2/s] and smaller than the experimental estimated value obtained from conductivity measurements (4.9×10−5 cm2/s). The difference between the diffusion constants calculated for the two models is correlated with a marked enhancement of the probability of reversal of the direction of motion of the migrating electron in flexible water. The self-diffusion constant of water using the rigid-molecules model [Ds=(3.6±0.4)×10−5 cm2/s] is also larger than that found for the flexible-water molecule model Ds=(2.3±0.2)×10−5] cm2/s], with the latter in agreement with the experimental value (Ds=2.3×10−5 cm2/s). Structural and dynamical aspects of hydrated electron transport are discussed.
    Type of Medium: Electronic Resource
    Signatur 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 89 (1988), S. 2242-2256 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dynamics and spectra of negatively charged water clusters, containing a single excess electron, are investigated. In our calculations the atomic water constituents of the clusters are treated classically while the excess electron is described quantum mechanically using the fast Fourier transform algorithm to solve the Schrödinger equation. Information about ground and excited electronic states corresponding to the equilibrium, finite temperature, ground-state ensemble configurations can be obtained by solving for these states for given nuclear configurations generated via quantum mechanical path-integral molecular dynamics simulations. As an alternative, more efficient way, we introduce the adiabatic simulation method which consists of propagating the nuclei in real time while concurrently annealing the electronic wave functions to their correct values corresponding to the instantaneous, dynamically generated nuclear configurations. The resulting trajectories can be used for analyzing nuclear motion in the ground electronic state as well as for calculating energy distributions for the ground and excited electronic states and the (vertical) excitation line shape. We study the cluster size effect on these quantities, and in particular, by comparing results for(H2O)−64 and (H2O)−128, we conclude that the vertical ionization potential increases while the vertical excitation energy to the bound excited state decreases for larger cluster sizes. For the smallest negatively charged water cluster (H2O)−2, where adiabatic separation of electronic and nuclear motion does not hold, we simulate the time evolution in the TDSCF approximation. The dynamics reveals the close correlation between the electronic binding energy and the cluster dipole, and provides information on intramolecular and intermolecular vibrational motion. Comparison of vibrational density of states evaluated from the nuclear trajectories of the negatively charged and the neutral dimer shows that most of the modes associated with intermolecular motions shift to the red upon electron attachment (a few modes, possibly those associated directly with the magnitude of the total molecular dipole, shift to the blue).
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 2716-2723 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper we explore the mechanisms of cluster isomerization induced by electron attachment to small, neutral Na4Cl4 clusters, with the localization of an excess electron inducing structural configurational changes within the cluster. The constant temperature quantum path integral molecular dynamics method was applied to obtain information of the structure and energetics of the cluster as well as the binding energy and the charge distribution of the excess electron for Na4Cl−4 clusters, over the temperature range of 50–1200 K. The attachment of an excess electron to the ionic cluster induced two types of configurational modifications, which can be traced to the role of the excess electron as a pseudonegative ion and to the partial neutralization of a single cation by the excess electron. Consequently, the induction of isomerization at moderately low temperatures, in conjunction with the appearance of new nuclear configurations of the negative cluster, which have no counterpart in the neutral parent cluster, are exhibited.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 8734-8740 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A semiempirical shell-correction method including ellipsoidal deformations is used to determine binding energies of open-shell, unpolarized 3HeN clusters. Shell effects, shapes, and other ground-state properties (like the chemical potential) are determined. 3HeN clusters are found to be substantially less deformed due to their relatively high surface energy as compared to that of alkali-metal clusters (e.g., sodium clusters). As a result, the size-evolutionary patterns associated with 3HeN clusters are significantly different than the corresponding ones for NaN clusters. In particular, odd–even oscillations and signatures of subshell closures are absent in the case of 3HeN clusters, while they are prominent in the case of alkali-metal clusters. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 387 (1997), S. 788-791 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Understanding the variation of a material's properties with size, form of aggregation and dimensionality is becoming important in the face of increasing miniaturization of electronic and mechanical devices. Experimental studies have focused on the preparation and characterization of solid-state ...
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 374 (1995), S. 607-616 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Friction, wear and lubrication between materials in contact are of fundamental importance in many pure and applied sciences. Owing to the development of experimental and computer-simulation techniques for studying these phenomena at the atomic scale, an understanding is beginning to emerge ...
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The Ionization Potentials of small LiN clusters are calculated with a Shell Correction Method. They are used to illustrate that, within the jellium approximation, deformed cluster shapes provide an adequate description of the observed systematic size dependence of the properties of simple metal clusters. Such deformation effects were overlooked in the analysis of Gardet et al. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 4309-4318 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Equilibrium structures, solvation forces, and conformational dynamics of thin confined films of n-hexadecane and squalane are investigated using a new grand canonical ensemble molecular dynamics method for simulations of confined liquids. The method combines constant pressure simulations with a computational cell containing solid surfaces and both bulk and confined liquid regions in equilibrium with each other. For both molecular liquids layered density oscillations in the confined films are found for various widths of the confining gap. The solvation force oscillations as a function of the gap width for the straight chain n-hexadecane liquid are more pronounced exhibiting attractive and repulsive regions, while for the branched alkane the solvation forces are mostly repulsive, with the development of shallow local attractive regions for small values of the gap width. Furthermore, the nature of the transitions between well-formed layered configurations is different in the two systems, with the n-hexadecane film exhibiting solid-like characteristics portrayed by step-like variations in the number of confined segments occurring in response to a small decrease in the gap width, starting from well-layered states of the film. On the other hand the behavior of the squalane film is liquid-like, exhibiting a monotonic continuous decrease in the number of confined segments as the gap width is decreased. These characteristics are correlated with structural properties of the confined films which, for n-hexadecane, exhibit enhanced layered ordering and in-plane ordered molecular arrangements, as well as with the relatively high tendency for interlayer molecular interdigitation in the squalane films. Reduced conformational (trans-guache) transition rates in the confined films, compared to their bulk values, are found, and their oscillatory dependence on the degree of confinement is analyzed, showing smaller transition rates for the well-formed layered states of the films. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 2498-2507 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Energetic, structural, and dynamical properties of solid-to-liquid and liquid-to-vapor interfaces and molecular evaporation and condensation processes from high-temperature liquid n-C6H14 and n-C16H34 films were investigated with molecular dynamics simulations. For hexadecane all evaporation events occurred via monomers while for hexane, evaporation of monomers as well as dimers were observed. For both alkane liquids the molecular evaporation mechanism is found to be sequential in nature, starting with an end segment of a molecule leaving the surface and subsequently the evaporation of the molecule occurs via sequential "dragging'' of the rest of the molecule. The condensation coefficients of vapor molecules onto the liquid surface are estimated as ∼0.9 for hexane and ∼1 for hexadecane. Evaporation is accompanied by significant molecular conformational changes. In hot liquid n-C16H34 the trans (t) and gauch (g+ and g−) dihedral conformations are distributed as (t,g+,g−)=(66,17,17) while in the vapor the distribution is almost uniform with a large decrease in the fraction of trans conformations, i.e., (33,31,36). On the other hand, for the shorter alkane hot liquid (t,g+,g−)=(72,14,14) while in the vapor the fraction of trans conformations is increased, i.e., (83,10,7). These results are discussed in light of theoretical treatments of evaporation processes.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...