International Journal of Quantum Chemistry

Cover image for Vol. 114 Issue 17

Special Issue: VIIIth Congress of the International Society for Theoretical Chemical Physics

September 5, 2014

Volume 114, Issue 17

Pages i–iv, 1097–1156

Issue edited by: Erkki Brändas, Ágnes Szabados, Péter Surján

  1. Cover Image

    1. Top of page
    2. Cover Image
    3. Perspectives
    4. Review
    5. Full Papers
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      Cover Image, Volume 114, Issue 17 (pages i–ii)

      Article first published online: 12 JUL 2014 | DOI: 10.1002/qua.24738

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      Positron spectroscopy is a remarkable, important tool in the fields of materials science and medicine. On page 1146 (DOI: 10.1002/qua.24641), Yuki Oba and Masanori Tachikawa report that theoretical modeling aids the interpretation of positron experiments and can predict the positron binding to large biomolecules. In the case of aspartame, a molecular orbital exists around the region with high electron density, indicating that the long-range electrostatic interaction plays the most crucial role in positron binding.

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      Inside Cover, Volume 114, Issue 17 (pages iii–iv)

      Article first published online: 12 JUL 2014 | DOI: 10.1002/qua.24739

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      Thermochemical quantities must be accompanied by uncertainties that unambiguously convey their believed accuracy, which combines the achieved precision and perceived trueness. Branko Rusic reports on page 1097 (DOI: 10.1002/qua.24605) that the uncertainties of electronic structure results can be quantified either by benchmarking (Type A) or estimation (Type B), and should adhere to the universally accepted standard in thermochemistry of expressing them as 95% confidence intervals. The ubiquitous Mean Absolute Deviation (MAD) severely underestimates the conventional uncertainty used in thermochemistry.

  2. Perspectives

    1. Top of page
    2. Cover Image
    3. Perspectives
    4. Review
    5. Full Papers
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      Uncertainty quantification in thermochemistry, benchmarking electronic structure computations, and Active Thermochemical Tables (pages 1097–1101)

      Branko Ruscic

      Article first published online: 11 JAN 2014 | DOI: 10.1002/qua.24605

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      Mean absolute deviation, frequently used to assess the accuracy of theoretical methods, significantly underestimates the conventional thermochemical uncertainty, and thus produces a number of unintended consequences. Two groups of procedures for determining the accuracy of computed thermochemical quantities are outlined: one relying on estimates that are based on experience, the other on benchmarking. Benchmarking state-of-the-art theory requires a source of highly accurate thermochemical data, such as Active Thermochemical Tables.

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      Polarizable embedding based on multiconfigurational methods: Current developments and the road ahead (pages 1102–1107)

      Erik D. Hedegård, Hans Jørgen Aa. Jensen and Jacob Kongsted

      Article first published online: 19 FEB 2014 | DOI: 10.1002/qua.24632

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      The polarizable embedding (PE) method is a multiscale approach which focuses on molecular response properties and spectroscopic constants. Recently, the PE method has been coupled to a multiconfiguration self-consistent field (MCSCF) approach. This method, denoted PE-MCSCF, finds application in the calculations of photosensitive proteins and transition metal complexes.

  3. Review

    1. Top of page
    2. Cover Image
    3. Perspectives
    4. Review
    5. Full Papers
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      Analytic energy derivatives in relativistic quantum chemistry (pages 1108–1127)

      Lan Cheng, Stella Stopkowicz and Jürgen Gauss

      Article first published online: 24 FEB 2014 | DOI: 10.1002/qua.24636

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      The current status of analytic-derivative theory in relativistic quantum chemistry for the efficient calculation of properties (geometries, electrical properties, etc.) is reviewed with a special emphasis on cost-effective schemes such as direct perturbation theory, spin-free four-component approaches, and exact two-component (X2C) theory.

  4. Full Papers

    1. Top of page
    2. Cover Image
    3. Perspectives
    4. Review
    5. Full Papers
    1. A density functional study on the pKa of small polyprotic molecules (pages 1128–1134)

      Takeshi Baba, Toru Matsui, Katsumasa Kamiya, Masayoshi Nakano and Yasuteru Shigeta

      Article first published online: 19 FEB 2014 | DOI: 10.1002/qua.24631

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      The acid dissociation constant and its logarithm (pKa) are often used to specify the position of protons in biomolecules. A novel scheme to compute pKa values based on quantum chemical calculations combined with a polarizable continuum model is applied to several biologically important small molecules in aqueous solution such as salicylic acid, histamine, and dopamine. These molecules have plural protonation sites whose inherent pKa determines which protons exist at a specific pH.

    2. Molecular switch properties of 7-hydroxyquinoline compounds (pages 1135–1145)

      András Csehi, Gábor J. Halász and Ágnes Vibók

      Article first published online: 24 FEB 2014 | DOI: 10.1002/qua.24639

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      7-Hydroxyquinoline derivatives are investigated as suitable molecular switches. To confirm the presence of conical intersections, nonadiabatic coupling terms must be derived and used in constructing the topological phase of the molecule. First-principle modeling can be also applied to understand the effect of various functional groups on the molecular switch properties of the core quinoline compound.

    3. Theoretical investigation of a positron binding to an aspartame molecule using the ab initio multicomponent molecular orbital approach (pages 1146–1149)

      Yuki Oba and Masanori Tachikawa

      Article first published online: 21 FEB 2014 | DOI: 10.1002/qua.24641

      Thumbnail image of graphical abstract

      Positron spectroscopy is a remarkable, important tool in the fields of materials science and medicine. Theoretical modeling aids the interpretation of positron experiments and can predict positron binding to large biomolecules. In the case of aspartame, molecular orbital exists around the region with high electron density, which indicates that long-range electrostatic interaction plays the most crucial role in positron binding.

    4. Quantum Monte Carlo for activated reactions at solid surfaces: Time well spent on stretched bonds (pages 1150–1156)

      Philip E. Hoggan and Ahmed Bouferguène

      Article first published online: 3 APR 2014 | DOI: 10.1002/qua.24676

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      Quantum Monte Carlo (QMC) methods are used to show that stretched N2 is significantly under-bound in density functional estimates. The deficit compared to QMC energies is used to locate a bond-lengththat behaves like the dissociation transition state. This geometry is adsorbed on Cu(111) and a QMC simulation of the combined system gives an indication of the dissociation barrier and its lowering compared to the gas phase. N radicals are the product of both channels.

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