Now showing items 196-215 of 247

    • Rare and Nonexistent Nitrosyls: Periodic Trends and Relativistic Effects in Ruthenium and Osmium Porphyrin-Based {MNO}7 Complexes 

      Demissie, Taye Beyene; Conradie, Jeanet; Vazquez-Lima, Hugo; Ruud, Kenneth; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-14)
      Relativistic and nonrelativistic density functional theory calculations were used to investigate rare or nonexistent ruthenium and osmium analogues of nitrosylhemes. Strong ligand field effects and, to a lesser degree, relativistic effects were found to destabilize {RuNO}<sup>7</sup> porphyrins relative to their {FeNO}<sup>7</sup> analogues. Substantially stronger relativistic effects account for ...
    • Real-space numerical grid methods in quantum chemistry 

      Frediani, Luca; Sundholm, Dage (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-03)
    • A really close look at molecules 

      Svenson, Johan (Journal article; Tidsskriftartikkel, 2013)
      With a “magnifying glass”, a highly sophisticated atomic force microscope (AFM) scientists have recently developed a technique that allows single molecule visualization with atomic resolution.
    • Recombinant expression and purification of an ATP-dependent DNA ligase from Aliivibrio salmonicida 

      Williamson, Adele Kim; Pedersen, Hege (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-05)
      The genome of the psychrophilic fish-pathogen Aliivibrio salmonicida encodes a putative ATP-dependent DNA ligase in addition to a housekeeping NAD-dependent enzyme. In order to study the structure and activity of the ATP dependent ligase in vitro we have undertaken its recombinant production and purification from an Escherichia coli based expression system. Expression and purification of this ...
    • Redetermination and H-atom refinement of (S)-(+)-ibuprofen. Corrigendum 

      Hansen, Lars Kr; Perlovich, German; Bauer-Brandl, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2006)
      [Erratum to document cited in CA140:010932]
    • Redetermination of 3-hydroxybenzamide 

      Hansen, Lars Kr; Perlovich, German; Bauer-Brandl, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2007)
    • Redetermination of p-ethoxyacetanilide (phenacetin) 

      Hansen, Lars Kr; Perlovich, German; Bauer-Brandl, Annette D (Journal article; Tidsskriftartikkel; Peer reviewed, 2006)
    • Relativistic effects on the NMR parameters of Si, Ge, Sn, and Pb alkynyl compounds: Scalar versus spin-orbit effects 

      Demissie, Taye Beyene (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-01)
      The NMR chemical shifts and indirect spin-spin coupling constants of 12 molecules containing <sup>29</sup>Si, <sup>73</sup>Ge, <sup>119</sup>Sn, and <sup>207</sup>Pb [X(CCMe)<sub>4</sub>, Me<sub>2</sub>X(CCMe)<sub>2</sub>, and Me<sub>3</sub>XCCH] are presented. The results are obtained from non-relativistic as well as two- and four-component relativistic density functional theory (DFT) calculations. ...
    • Relativistic four-component calculations of Buckingham birefringence using London atomic orbitals 

      Bast, Radovan; Ruud, Kenneth; Rizzo, Antonio; Helgaker, Trygve (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      We present the first relativistic study of the electric-field-gradient induced birefringence (Buckingham birefringence), with application to the series of molecules CX2 (X = O, S, Se, Te). A recently developed atomic-orbital-driven scheme for the calculation of time-dependent molecular properties using one-, two- and four-component relativistic wave functions (Bast et al. in Chem Phys 356:177, 2009) ...
    • Relativistic four-component calculations of indirect nuclear spin-spin couplings with efficient evaluation of the exchange-correlation response kernel 

      Kristkova, Anezka; Komorovsky, Stanislav; Repisky, Michal; Malkin, Vladimir G.; Malkina, Olga L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-03-16)
      In this work, we report on the development and implementation of a new scheme for efficient calculation of indirect nuclear spin-spin couplings in the framework of four-component matrix Dirac-Kohn-Sham approach termed matrix Dirac-Kohn-Sham restricted magnetic balance resolution of identity for J and K, which takes advantage of the previous restricted magnetic balance formalism and the density ...
    • Resolution-of-identity accelerated relativistic two- and four-component electron dynamics approach to chiroptical spectroscopies 

      Konecny, Lukas; Kadek, Marius; Komorovsky, Stanislav; Ruud, Kenneth; Repisky, Michal (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-27)
      We present an implementation and application of electron dynamics based on real-time time-dependent density functional theory (RT-TDDFT) and relativistic 2-component X2C and 4-component Dirac–Coulomb (4c) Hamiltonians to the calculation of electron circular dichroism and optical rotatory dispersion spectra. In addition, the resolution-of-identity approximation for the Coulomb term (RI-J) is introduced ...
    • Response properties of embedded molecules through the polarizable embedding model 

      Steinmann, Casper; Reinholdt, Peter; Nørby, Morten Steen; Kongsted, Jacob; Olsen, Jógvan Magnus Haugaard (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-04)
      The polarizable embedding (PE) model is a fragment‐based quantum‐classical approach aimed at accurate inclusion of environment effects in quantum‐mechanical response property calculations. The aim of this tutorial review is to give insight into the practical use of the PE model. Starting from a set of molecular structures and until you arrive at the final property, there are many crucial details to ...
    • Rhodium-Catalyzed Hydrocarboxylation: Mechanistic Analysis Reveals Unusual Transition State for Carbon–Carbon Bond Formation 

      Pavlovic, Ljiljana; Vaitla, Janakiram; Bayer, Annette; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-12)
      The mechanism of rhodium-COD-catalyzed hydrocarboxylation of styrene derivatives and α,β-unsaturated carbonyl compounds with CO<sub>2</sub> has been investigated using density functional theory (PBE-D2/IEFPCM). The calculations support a catalytic cycle as originally proposed by Mikami and co-workers including β-hydride elimination, insertion of the unsaturated substrate into a rhodium–hydride bond, ...
    • Rhodium-Catalyzed Synthesis of Sulfur Ylides via in Situ Generated Iodonium Ylides 

      Vaitla, Janakiram; Hopmann, Kathrin H.; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-22)
      A convenient strategy for the synthesis of sulfur ylides via rhodium-catalyzed coupling of in situ generated iodonium ylides with sulfides or sulfoxides has been developed. A wide range of sulfur ylides were obtained in moderate to good yields from inexpensive sulfur compounds and active methylene compounds with a short reaction time (MW, 5–10 min) or 12–16 h at rt. Furthermore, these sulfoxonium ...
    • Role of zero-point vibrational corrections to carbon hyperfine coupling constants in organic pi radicals 

      Chen, Xiao; Rinkevicius, Zilvinas; Ruud, Kenneth; Ågren, Hans (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      By analyzing a set of organic π radicals, we demonstrate that zero-point vibrational corrections give significant contributions to carbon hyperfine coupling constants, in one case even inducing a sign reversal for the coupling constant. We discuss the implications of these findings for the computational analysis of electron paramagnetic spectra based on hyperfine coupling constants evaluated at the ...
    • Rotational averaging of multiphoton absorption cross sections 

      Friese, Daniel Henrik; Beerepoot, Maarten T. P.; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • Screening and Design of Inhibitor Scaffolds for the Antibiotic Resistance Oxacillinase-48 (OXA-48) through Surface Plasmon Resonance Screening 

      Lund, Bjarte Aarmo; Christopeit, Tony; Guttormsen, Yngve; Bayer, Annette; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-11)
      The spread of antibiotic resistant bacteria is a global threat that shakes the foundations of modern healthcare. β-Lactamases are enzymes that confer resistance to β-lactam antibiotics in bacteria, and there is a critical need for new inhibitors of these enzymes for combination therapy together with an antibiotic. With this in mind, we have screened a library of 490 fragments to identify starting ...
    • Screening of variable importance for optimizing electrodialytic remediation of heavy metals from polluted harbour sediments 

      Pedersen, Kristine Bondo; Lejon, Tore; Ottosen, Lisbeth M.; Jensen, Pernille E. (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-04-15)
      Using multivariate design and modelling, optimal conditions for electrodialytic remediation (EDR) of heavy metals were determined for polluted harbour sediments from Hammerfest harbour located in the geographic Arctic region of Norway. The comparative importance of the variables; current density, remediation time, light/no light, the liquid-solid ratio and stirring rate of the sediment suspension ...
    • Sensitive on-chip methane detection with a cryptophane-A cladded Mach-Zehnder interferometer 

      Dullo, Firehun Tsige; Lindecrantz, Susan; Jagerska, Jana; Hansen, Jørn H; Engqvist, Stig Olov Magnus; Solbø, Stian; Hellesø, Olav Gaute (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-24)
      We report a methane sensor based on an integrated Mach-Zehnder interferometer, which is cladded by a styrene-acrylonitrile film incorporating cryptophane-A. Cryptophane-A is a supramolecular compound able to selectively trap methane, and its presence in the cladding leads to a 17-fold sensitivity enhancement. Our approach, based on 3 cm-long low-loss Si3N4 rib waveguides, results in a detection limit ...
    • Shape-dependent electronic excitations in metallic chains 

      Gao, Bin; Ruud, Kenneth; Luo, Yi (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)