International Journal of Quantum Chemistry

Cover image for Vol. 113 Issue 17

September 5, 2013

Volume 113, Issue 17

Pages i–iv, 2019–2089

  1. Cover Image

    1. Top of page
    2. Cover Image
    3. Review
    4. Tutorial Review
    5. Full Papers
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      Cover Image, Volume 113, Issue 17 (pages i–ii)

      Version of Record online: 19 JUL 2013 | DOI: 10.1002/qua.24515

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      Visualization of an energy landscape surrogate for a system of 2001 Au nanoclusters computed using the CrystalFp fingerprinting method is presented by Mario Valle on page 2040 (DOI: 10.1002/qua.24480). Each Au nanocluster is represented as a point in a 73-dimensional space. These points are then projected to a plane while preserving as much as possible their inter-points distances. The represented plane interpolates the points with each of them displaced in the vertical direction by its per atom energy. The resulting surface is a fair representation of two energy minima and the energy barrier between them.

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      Inside Cover, Volume 113, Issue 17 (pages iii–iv)

      Version of Record online: 19 JUL 2013 | DOI: 10.1002/qua.24516

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      An understanding of molecular periodicity that has a basis in quantum states is highly desirable. The article by Ray Hefferlin, Jonathan Sackett, and Jeremy Tatum on page 2078 (DOI: 10.1002/qua.24469) explores this possibility through specific studies of diatomic systems that successively approach the formation of a rare-gas molecule. Molecules echo atomic periodicity, because properties for series of molecules follow a periodic behavior defined by molecular magic numbers. In the case of many band systems, it is the ratio of the force constants of the upper and lower states that determines the periodic behavior.

  2. Review

    1. Top of page
    2. Cover Image
    3. Review
    4. Tutorial Review
    5. Full Papers
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      TD-DFT benchmarks: A review (pages 2019–2039)

      Adèle D. Laurent and Denis Jacquemin

      Version of Record online: 9 APR 2013 | DOI: 10.1002/qua.24438

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      Time-dependent density functional theory has become the most widely used tool to investigate excited state properties. However, the selection of an adequate exchange-correlation functional remains a major issue. In this review, the results obtained through recent benchmarks are summarized and several properties considered: vertical and adiabatic transition energies, dipoles, geometries, oscillator strengths, and vibrational signatures. The review concludes with a set of general guidelines for active practitioners.

  3. Tutorial Review

    1. Top of page
    2. Cover Image
    3. Review
    4. Tutorial Review
    5. Full Papers
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      Visualization: A cognition amplifier (pages 2040–2052)

      Mario Valle

      Version of Record online: 31 MAY 2013 | DOI: 10.1002/qua.24480

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      Computational codes produce huge quantities of numbers, but what scientists seek is understanding. Visualization, transforming data into graphical structures, can enhance research effectiveness by leveraging human visual perceptual capabilities. In this tutorial, after analyzing a short definition of visualization, its major concepts will be seen in action—hands-on—using a popular chemistry visualization tool. The tutorial closes discussing paths for continued exploration of the future potential of these visualization techniques and tools.

  4. Full Papers

    1. Top of page
    2. Cover Image
    3. Review
    4. Tutorial Review
    5. Full Papers
    1. Superconductivity from repulsive electronic correlations on alternant cuprate and iron-based lattices (pages 2053–2059)

      Lawrence J. Dunne and Erkki J. Brändas

      Version of Record online: 23 MAR 2013 | DOI: 10.1002/qua.24437

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      High-temperature superconductivity can be induced by repulsive electronic correlations. Time-reversed electron pairs on cuprate and iron-based pnictide and chalcogenide alternant lattices can interact with a short-range Coulomb repulsion and a weaker longer range attractive tail. Such interacting electrons can collectively correlate to produce superconductivity. The alternant lattice structure is the key stabilizing feature of such a mechanism giving high-temperature superconductivity with inline image and s± condensate symmetries.

    2. Theoretical investigation of the alloxan–dialuric acid redox cycle (pages 2060–2069)

      Rita Kakkar and Mamta Bhandari

      Version of Record online: 23 MAR 2013 | DOI: 10.1002/qua.24441

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      Alloxan has long been used to induce diabetes in experimental animals in studies on diabetes mellitus, a metabolic disorder that affects several million people worldwide. The alloxan–dialuric acid redox cycle is believed to be responsible for the diabetogenecity of alloxan. Herein, the mechanism involved in this redox cycling is investigated, and it is found that alloxan is reduced by glutathione to the dialuric acid anion, which undergoes aerial oxidation to generate cytotoxic superoxide radicals, causing β-cell toxicity.

    3. Electronic structure of francium (pages 2070–2077)

      Alexander P. Koufos and Dimitrios A. Papaconstantopoulos

      Version of Record online: 13 MAY 2013 | DOI: 10.1002/qua.24466

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      Little is known about the properties of the heaviest alkali metal, francium. This article provides the first electronic structure study of francium while completing a systematic study of the other alkalis. Theoretically, the alkalis should become superconductors under pressure. Lithium has been the only one experimentally verified. This study suggests that the increased d-character of the states at the Fermi level is the mechanism for superconductivity under pressure.

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      Why do molecules echo atomic periodicity? (pages 2078–2089)

      Ray Hefferlin, Jonathan Sackett and Jeremy Tatum

      Version of Record online: 30 MAY 2013 | DOI: 10.1002/qua.24469

      Thumbnail image of graphical abstract

      A quantum mechanical understanding of molecular periodicity that has an atomic basis is highly desirable. This paper explores this question through specific studies of diatomic systems that successively approach the formation of a rare-gas molecule. The results indicate that molecules do indeed echo atomic periodicity, while basing this new understanding in more rigorous quantum mechanical terms. Open problems in obtaining a complete set of upper and ground state configurations of main-group diatomics remain.

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