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  • 1
    Electronic Resource
    Electronic Resource
    Construction of an ordered genomic library of Mycoplasma genitalium
    Amsterdam : Elsevier
    Gene 150 (1994), S. 27-34 
    Details
    ISSN: 0378-1119
    Keywords: Cloning ; MgPa ; cosmid ; genome size ; mollicutes ; pathogen ; physical map
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0378-1119(94)90853-2
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  • 2
    Electronic Resource
    Electronic Resource
    A first principles study of CH3 dehydrogenation on Ni(111) (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 8120-8125 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Density functional theory with gradient corrections and spin polarization has been used to study the dehydrogenation of CH3 on Ni(111), a crucial step in many important catalytic reactions. The reaction, CH3(ads)→CH2(ads)+H(ads), is about 0.5 eV endothermic with an activation energy of more than 1 eV. The overall reaction pathway is rather intriguing. The C moiety translates from a hcp to a fcc site during the course of the reaction. The transition state of the reaction has been identified. The CH3 species is highly distorted, and both C and the active H are centered nearly on top of a row of Ni atoms with a long C–H bond length of 1.80 Å. The local density of states coupled with examination of the real space distribution of individual quantum states has been used to analyze the reaction pathway. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481412
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  • 3
    Electronic Resource
    Electronic Resource
    A density functional theory study of CH2 and H adsorption on Ni(111) (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 6006-6014 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ab initio total energy calculations within the density functional theory framework have been used to study the adsorption of CH2 and H as well as the coadsorption of CH2 and H on Ni(111). H binds strongly at threefold hollow sites with calculated adsorption energies of 2.60 and 2.54 eV at the face-centered-cubic (fcc) and hexagonal-close-packed (hcp) hollow sites, respectively. Adsorption energies and H-Ni distances are found to agree well with both experimental and theoretical results. CH2 adsorbs strongly at all high symmetry sites with calculated adsorption energies of 3.26, 3.22, 3.14 and 2.36 eV at the fcc, hcp, bridge and top sites, respectively. Optimized structures are reported at all sites, and, in the most stable hollow sites there is considerable internal reorganization of the CH2 fragment. The CH2 molecule is tilted, the hydrogens are inequivalent and the C-H bonds are lengthened relative to the gas phase. In the CH2-H coadsorption systems the adsorbates have a tendency to move toward bridge sites. The bonding of all adsorbates to the surface is analyzed in detail. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481173
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  • 4
    Electronic Resource
    Electronic Resource
    Site symmetry dependence of repulsive interactions between chemisorbed oxygen atoms on Pt{100}-(1×1) (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 1210-1215 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ab initio total energy calculations using density functional theory with the generalized gradient approximation have been performed for the chemisorption of oxygen atoms on a Pt{100}-(1×1) slab. Binding energies for the adsorption of oxygen on different high-symmetry sites are presented. The bridge site is the most stable at a coverage of 0.5 ML, followed by the fourfold hollow site. The atop site is the least stable. This finding is rationalized by analyzing the "local structures" formed upon oxygen chemisorption. The binding energies and heats of adsorption at different oxygen coverages show that pairwise repulsive interactions are considerably stronger between oxygen atoms occupying fourfold sites than those occupying bridge sites. Analysis of the partial charge densities associated with Bloch states demonstrates that the O–Pt bond is considerably more localized at the bridge site. These effects cause a sharp drop in the heats of adsorption for oxygen on hollow sites when the coverage is increased from 0.25 to 0.5 ML. Mixing between oxygen p orbitals and Pt d orbitals can be observed over the whole metal d-band energy range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.473217
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  • 5
    Electronic Resource
    Electronic Resource
    A density functional theory study of CO oxidation on Ru(0001) at low coverage (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 10564-10570 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have performed ab initio density functional theory calculations with the generalized gradient approximation to investigate CO oxidation on Ru(0001). Several reaction pathways and transition states are identified. A much higher reaction barrier compared to that on Pt(111) is determined, confirming that the Ru is very inactive for CO oxidation under UHV conditions. The origin of the reaction barrier was analyzed. It is found that in the transition state the chemisorbed O atom sits in an unfavorable bonding site and a significant competition for bonding with the same substrate atoms occurs between the CO and the chemisorbed O, resulting in the high barrier. Ab initio molecular dynamics calculations show that the activation of the chemisorbed O atom from the initial hcp hollow site (the most stable site) to the bridge site is the crucial step for the reaction. The CO oxidation on Ru(0001) via the Eley–Rideal mechanism has also been investigated. A comparison with previous theoretical work has been made. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481690
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  • 6
    Electronic Resource
    Electronic Resource
    Physical origin of the high reactivity of subsurface hydrogen in catalytic hydrogenation (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 1343-1345 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In the catalytic hydrogenation of hydrocarbons, subsurface hydrogen is known experimentally to be much more reactive than surface hydrogen. We use density functional theory to identify low-energy pathways for the hydrogenation of methyl adsorbed on Ni(111) by surface and subsurface hydrogen. The metastability of subsurface hydrogen with respect to chemisorbed hydrogen is mainly responsible for the low activation barrier for subsurface reactions. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479392
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  • 7
    Electronic Resource
    Electronic Resource
    Ab initio diffusional potential energy surface for CO chemisorption on Pd{110} at high coverage: Coupled translation and rotation (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 8103-8109 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The ground state potential energy surface for CO chemisorption across Pd{110} has been calculated using density functional theory with gradient corrections at monolayer coverage. The most stable site corresponds well with the experimental adsorption heat, and it is found that the strength of binding to sites is in the following order: pseudo-short-bridge〉atop〉long-bridge〉hollow. Pathways and transition states for CO surface diffusion, involving a correlation between translation and orientation, are proposed and discussed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.475073
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  • 8
    Electronic Resource
    Electronic Resource
    Resonant level lifetime in GaAs-AlAs double-barrier structures including Γ-X mixing (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 8387-8391 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A quantitative model for calculation of the lifetime of quasibound states, including the Γ-X transfer, in a AlAs-GaAs-AlAs double-barrier structure is presented. When device is designed that a Γ-like energy level approaches to an X-like energy level, anticrossing of the Γ-X transition occurs and the lifetime of the state can be several orders larger than that of a pure Γ system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348923
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  • 9
    Electronic Resource
    Electronic Resource
    Insight into why the Langmuir–Hinshelwood mechanism is generally preferred (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 4379-4381 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In heterogeneous catalysis, the two main reaction mechanisms which have been proposed are the Langmuir–Hinshelwood and the Eley–Rideal. For the vast majority of surface catalytic reactions, it has been accepted that the Langmuir–Hinshelwood mechanism is preferred. In this study, we investigate catalytic CO oxidation on Pt(111). It is found that reaction barriers for Langmuir–Hinshelwood mechanisms actually tend to be higher than those for Eley–Rideal ones. An explanation is presented as to why it is still more probable for the reaction to proceed via the Langmuir–Hinshelwood mechanism, despite its higher reaction barrier. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1458938
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  • 10
    Electronic Resource
    Electronic Resource
    A first principles study of methanol decomposition on Pd(111): Mechanisms for O–H bond scission and C–O bond scission (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 7182-7186 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: There is some dispute as to whether methanol decomposition occurs by O–H bond scission or C–O bond scission. By carrying out density functional theory calculations, we investigate both scenario of the reaction pathways of methanol decomposition on a Pd(111) surface. It is shown that the O–H bond scission pathway is much more energetically favorable than the C–O bond scission pathway. The high reaction barrier in the latter case is found to be due to the poor bonding abilities of CH3 and OH with the surface at the reaction sites. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1405157
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