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  • 1
    Electronic Resource
    Electronic Resource
    Locating all transition states and studying the reaction pathways of potential energy surfaces (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 9259-9295 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We propose a new method for calculating all stationary states, including saddle points of all orders, of a potential energy surface based on the αBB deterministic branch and bound global optimization algorithm. This method is based on rigorous optimization methods and offers a theoretical guarantee of enclosing all solutions to the equation ∇V=0. We apply this method to Murrel–Sorbie analytic potential energy surfaces of HCN, HSiN, HBO, and CS2, and to the Empirical Conformational Energy Program for Peptides (ECEPP/3) potential energy surfaces of alanine, alanine dipeptide, and tetra-alanine. For alanine, alanine dipeptide, and tetra-alanine, we proceed to analyze the topography of the potential energy surface by calculating reaction pathways, transition rate matrices, time-evolution of occupation probabilities, and rate disconnectivity graphs. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478850
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  • 2
    Electronic Resource
    Electronic Resource
    An isomeric 19+ state of the $$\pi h_{{9 \mathord{\left/ {\vphantom {9 2}} \right. \kern-\nulldelimiterspace} 2}}^2 i_{1{3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-\nulldelimiterspace} 2}} vg_{{9 \mathord{\left/ {\vphantom {9 2}} \right. \kern-\nulldelimiterspace} 2}} (j^{ - 2} )_{0^ + }$$ configuration in 85 210 At125 and the question of isospin dependence in the two-particle core polarization (1978)
    Springer
    The European physical journal 284 (1978), S. 357-369 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Usingα-particles of energies 35–51 MeV and in-beam conversion electron andγ-spectroscopy techniques, a 4.0±1.7 μs core-excited 19+ isomeric state in210At with ag-factor of 0.737±0.025 has been observed at an excitation energy of 4027.7 keV. The 19+ state is suggested to have the $$\pi h_{{9 \mathord{\left/ {\vphantom {9 2}} \right. \kern-\nulldelimiterspace} 2}}^2 i_{1{3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-\nulldelimiterspace} 2}} vg_{{9 \mathord{\left/ {\vphantom {9 2}} \right. \kern-\nulldelimiterspace} 2}} (j^{ - 2} )_{0^ + }$$ configuration with maximum alignment of the angular momenta. The total two-particle core polarization due to theh 9/2 andi 13/2 protons and theg 9/2 neutron was found to be −68±20 keV as compared to −125±18 keV for the 29/2+ isomeric state of the $$\pi h_{{9 \mathord{\left/ {\vphantom {9 2}} \right. \kern-\nulldelimiterspace} 2}}^2 i_{1{3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-\nulldelimiterspace} 2}} v(j^{ - 2} )_{0^ + }$$ configuration in209At, which only differs by ag 9/2 neutron. This observation indicates an isospin effect in the two-particle core polarization, which is also supported by recent discoveries of core-excited high-spin levels in208Bi using (d, α)-reactions. Thus in the orbits concerned, a proton-proton pair seems to have a much larger quadrupole polarization effect than a neutron-proton pair.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01422102
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  • 3
    Electronic Resource
    Electronic Resource
    Evidence for two-particle core polarization in the isomeric 29/2+ and 21/2− states of the $$\pi \left( {h_{{9 \mathord{\left/ {\vphantom {9 2}} \right. \kern-\nulldelimiterspace} 2}}^2 } \right)_{8^ + } i_{1 {3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-\nulldelimiterspace} 2}} v\left( {j^{ - 2} } \right)_{0^ + } $$ and $$\pi \left( {h_{{9 \mathord{\left/ {\vphantom {9 2}} \right. \kern-\nulldelimiterspace} 2}}^3 } \right)v\left( {j^{ - 2} } \right)_{0^ + } $$ configurations in209At (1975)
    Springer
    The European physical journal 273 (1975), S. 291-304 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Usingα-particles in the energy range 42–51 MeV, the209Bi(α, 4n)209At reaction was studied with the intention of investigating the properties of excited high spin states in209At. In-beam prompt and delayed gamma-ray and conversion electron spectroscopy reveal two isomeric states at 2429 and 1428 keV having the half-lives of 875±100 ns and 25±1 ns, respectively. The spins and parities of these states are found to be 29/2+ and 21/2−, respectively. Theg-factors of the isomeric states are 1.06±0.02 and 0.88±0.06, which, within the experimental errors, are the same as theg-factors of the corresponding states in211At. This suggests that the isomeric states are due to the $$\pi \left( {h_{{9 \mathord{\left/ {\vphantom {9 2}} \right. \kern-\nulldelimiterspace} 2}}^2 } \right)_{8^ + } i_{1 {3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-\nulldelimiterspace} 2}} v\left( {j^{ - 2} } \right)_{0^ + } $$ and $$\pi \left( {h_{{9 \mathord{\left/ {\vphantom {9 2}} \right. \kern-\nulldelimiterspace} 2}}^3 } \right)v\left( {j^{ - 2} } \right)_{0^ + } $$ configurations, respectively. The deviation between the calculated and experimentally found excitation energies of the isomeric levels are −146±26 and +72 ±26 keV. This deviation which in cases of a208Pb-core usually is smaller than 15 keV, is likely to be due to the neglect of the interaction between two particles via the exchange of virtual 2+ phonons in the206Pb core. This two-particle polarization interaction is found to be approximately described by aP 2-force.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01410012
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  • 4
    Electronic Resource
    Electronic Resource
    High spin states in205Pb and a precision test of the nuclear shell model for three nucleons (1976)
    Springer
    The European physical journal 277 (1976), S. 273-290 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Using the204Hg(α, 3n) reaction withα-particles of about 40 MeV, we have proved by applying nowadays conventionalγ-ray spectroscopy in-beam technique, that there are two isomeric states in205Pb at the excitation energies 5,161.3 and 3,195.5 keV having the half-lives 71±3 and 217±5 ns, respectively. These isomeric states have spins and parities 33/2+ and 25/2− and are mainly due to thei 13 2/−3 andi 13 2/−2 p 1 2/−1 configurations, respectively. This conclusion is supported by the experimentalg-factors of these states being −0.159±0.008 and −0.0676±0.0011, respectively. It is furthermore shown that theE2 effective neutron charge is the same forE2 transitions from the 33/2+ state in205Pb and from the 12+ state in206Pb as required by the assumption that the208Pb core is responsible for the totalE2 strength of the neutron holes, and that these states are due to thei 13 2/−3 andi 13 2/−2 configurations. The calculatedB(E3) values ofE3 transitions from isomeric states in205Pb and206Pb agree reasonably well with the experimental values as expected from the assumption that theE3-strength should come from particle coupling to the octupole states of the208Pb core. The energies of the six most well established excited states in205Pb with angular momenta in the region 19/2–33/2 were calculated using empirical single-particle energies, empirical two-particle interactions and angular momentum algebra. The average deviation between experimental and calculated energies is −3 keV and the root mean square deviation 6 keV as compared to the uncertainty ± 5 keV in the nuclear masses used in the calculation. For the orbits concerned the shell model is thus valid with an extremely high precision. The contribution of effective three-particle interaction in these orbits must consequently be less than about 5 keV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01415603
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  • 5
    Electronic Resource
    Electronic Resource
    Finite element analysis of flow, heat transfer, and free interfaces in an electron-beam vaporization system for metals (1998)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 26 (1998), S. 637-655 
    Details
    ISSN: 0271-2091
    Keywords: liquid flow ; energy transport ; electron-beam ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A numerical analysis is made of the liquid flow and energy transport in a system to evaporate metals. The energy from an electron-beam heats an axisymmetric metal disk supported by a water-cooled platform. Metal evaporates from the surface of a hot pool of liquid which is surrounded by a shell of its own solid. Flow in the pool is strongly driven by temperature-induced buoyancy and capillary forces, and is located in the transition region between laminar and turbulent flow. The evaporation rate is strongly influenced by the locations of the free boundaries. A modified finite element method is used to calculate the steady state flow and temperature fields coupled with the interface locations. The mesh is structured with spines that stretch and pivot as the interfaces move. The discretized equations are arranged in an ‘arrow’ matrix and are solved using the Newton-Raphson method. The electron-beam power and platform contact resistance are varied for cases involving the evaporation of aluminum. The results reveal the interaction of liquid flow, heat transfer and free interfaces. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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