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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 9018-9027 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We describe light emission from the complex formed during ion–atom collisions, that arises from electronic charge transfer and the related oscillatory dipole of the complex. This is treated in an eikonal/time-dependent Hartree–Fock approach which accounts for coupling of electronic and nuclear motions and generates the time-dependent dipole of the complex. Calculations were done for H++H with a basis set of travelling atomic functions, for collision energies of 100, 250, and 1000 eV, to obtain the energy emitted per solid angle versus both time and the light frequency. Results are presented for the intensity components of the light emitted parallel and perpendicular to the incoming projectile H+ velocity. Light emission is found to last several femtoseconds, and to be distributed over ultraviolet frequencies. The intensity of light emitted by the complex H2+ increases as collision energies are lowered. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 594-597 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Recent technological advances in the production of polymer particles suggests the feasibility of generating polymer nanoparticles from solution with discrete electronic structure in close analogy with quantum dots. We call these new particles quantum drops, which have controllable physical properties including radius, composition, chemical potential, and magnetic properties. We consider the electronic properties of electrons confined on the surface of these spherical polymer nanoparticles using a new Hamiltonian and semiclassical quantization. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 5141-5148 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A semiclassical approach to the calculation of thermal rate constants, based on the flux–flux autocorrelation function method, is presented with its applications. The autocorrelation function is generated along classical trajectories using a classical interpretation of the Boltzmannized flux operator. The activation energies for considered reactions are calculated using the G2/MP2 procedure. The forces are generated using a new parametrization of the PM3 NDDO Hamiltonian optimized for accurate gradients. Thermal rate constants for hydrogen abstraction from ethane and haloethanes by hydroxyl radical serve as a first test of this approach. Calculated results are in good agreement with cumulative rate constants for all systems considered over a range of temperature including room temperature. The approach is able to distinguish between α and β abstraction with a result for fluoroethane at room temperature that is consistent with the available experiment and trends that are in line with those expected. © 2001 American Institute of Physics.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 38 (1990), S. 781-790 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A time-dependent molecular orbital approach has been developed for describing the dynamics of atomic and molecular interactions. Equations derived for the time-dependent electronic density matrices in the TDHF approximation are locally linearized in time with the use of a time-dependent reference density. It contains a time-dependent driving term due to the nuclear motions. Nuclear motions are obtained from the gradients of effective potentials which change with electronic states and account for couplings of nuclear and electronic motions. Results are presented for electron transfer in proton-hydrogen collisions, to compare to other calculations.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 545-558 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A time-dependent molecular orbital method has been developed to study charge transfer in collisions of ions with metal surfaces at energies between 1 and 100 au. A set of localized basis functions consisting of generalized Wannier functions for the surface and s- and p-atomic functions for the ion, is used to separate the system into primary and secondary regions. An effective Hamiltonian and time-dependent equations for the electron density matrix are obtained in the primary region, where most charge transfer occurs. The equations for the electron density matrix are solved with a linearization scheme. The method is suitable to study atomic orbital orientation for collisions of ions and surfaces. A model calculation for Na+ + W(110) collisions with a prescribed trajectory is presented. The interaction potentials between the W(110) surface and Na+ 3s and 3p orbitals are calculated from Na+ pseudopotentials. Results show that the yield of neutralized atoms in 3p states changes as the collision energy is lowered.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 1469-1477 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We study the intensity and polarization of light emitted during slow ion-atom collisions. We describe the nuclei as moving along classical trajectories while the electronic rearrangement is treated using time-dependent molecular orbitals. The intensity of emitted light is calculated from the diatomic time-dependent dipole. We evaluate the diatomic dipole matrix elements involving 1s, 2s, and 2p traveling atomic orbitals suitable for time-dependent collision studies. We calculate the intensity and the polarization of light emitted in p + H(1s) collisions at kinetic energies from 10 to 1000 eV, for several impact parameters, changing over time. The emitted intensity goes through a maximum as the collision energy increases and lasts between 10 and 1 fs; the polarized light components parallel and perpendicular to the incoming beam direction show pronounced dependences on impact parameters and time. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 64 (1997), S. 561-570 
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Advances in magnet construction technology have made magnets available with continuous fields of nearly 50 T and with bores of sufficient diameter for experiments. In addition to these magnets, already in use at the National High Magnetic Field Laboratory (NHMFL), semicontinuous pulsed sources of 100 T are anticipated in the near future. At its Los Alamos campus, the NHMFL has detonated pulsed magnets of over 1000 T. It thus becomes possible to investigate the behavior of molecules in strong fields with an eye to field-induced changes in such quantities as geometrical and electronic properties, spectroscopic properties, and reactivities. Theory is a useful probe for these quantities and serves to screen among possible candidates for experiments. In this contribution, we report preliminary results on the calculation of electronic properties of H2+, H2, and LiH, the simplest of molecules. Initial indications are that for increasing applied field strength, molecular bond lengths decrease and binding energies increase, with a concomitant increase in vibrational frequencies. Field-induced changes in these quantities, as well as in ground-state molecular potential energy surfaces are discussed, and suggestions are made for further investigations, both theoretical and experimental.    © 1997 John Wiley & Sons, Inc. Int J Quant Chem 64: 561-570, 1997
    Additional Material: 7 Ill.
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  • 8
    Publication Date: 2016-06-01
    Print ISSN: 0031-9228
    Electronic ISSN: 1945-0699
    Topics: Physics
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  • 9
    Publication Date: 1997-11-01
    Print ISSN: 1050-2947
    Electronic ISSN: 1094-1622
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
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  • 10
    Publication Date: 1996-03-01
    Print ISSN: 1050-2947
    Electronic ISSN: 1094-1622
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
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