Viser treff 340-359 av 527

    • Open-ended recursive approach for the calculation of multiphoton absorption matrix elements 

      Friese, Daniel Henrik; Beerepoot, Maarten T. P.; Ringholm, Magnus; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-02-11)
      We present an implementation of single residues for response functions to arbitrary order using a recursive approach. Explicit expressions in terms of density-matrix-based response theory for the single residues of the linear, quadratic, cubic, and quartic response functions are also presented. These residues correspond to one-, two-, three- and four-photon transition matrix elements. The newly ...
    • Open-Ended Recursive Calculation of Single Residues of Response Functions for Perturbation-Dependent Basis Sets 

      Friese, Daniel Henrik; Ringholm, Magnus; Gao, Bin; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-09-09)
      We present theory, implementation, and applications of a recursive scheme for the calculation of single residues of response functions that can treat perturbations that affect the basis set. This scheme enables the calculation of nonlinear light absorption properties to arbitrary order for other perturbations than an electric field. We apply this scheme for the first treatment of two-photon circular ...
    • Open-ended response theory with polarizable embedding: multiphoton absorption in biomolecular systems 

      Steindal, Arnfinn Hykkerud; Beerepoot, Maarten; Ringholm, Magnus; List, Nanna Holmgaard; Ruud, Kenneth; Kongsted, Jacob; Olsen, Jógvan Magnus Haugaard (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-09-19)
      We present the theory and implementation of an open-ended framework for electric response properties at the level of Hartree–Fock and Kohn–Sham density functional theory that includes effects from the molecular environment modeled by the polarizable embedding (PE) model. With this new state-of-the-art multiscale functionality, electric response properties to any order can be calculated for molecules ...
    • The optical activity of beta, gamma-enones in ground and excited states using circular dichroism and circularly polarized luminescence 

      Pecul, Magdalena; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      The circularly polarized luminescence (CPL) and electronic circular dichroism (CD) spectroscopic parameters corresponding to the n ← π* and n → π* transitions, respectively, have been calculated for selected β,γ-enones using density functional theory. For the smallest β,γ-enone, (1R,4R)-bicyclo[2.2.1]hept-5-en-2-one (norbornenone), coupled-cluster calculations have also been carried out. The ...
    • An optimised method for electrodialytic removal of heavy metals from harbour sediments 

      Pedersen, Kristine Bondo; Jensen, Pernille E.; Ottosen, Lisbeth M.; Lejon, Tore (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-08-10)
      A 2-compartment electrodialytic cell set-up for treatment of solid materials has in many respects proven superior to other types of cells in removing heavy metals from sediments. Most notably, remediation times were shorter, energy consumption was lower and higher removal efficiencies were observed. By employing multivariate modelling and investigating additional experimental variables, the ...
    • Organometallic Chemistry for Enabling Carbon Dioxide Utilization 

      Hazari, Nilay; Iwasawa, Nobuharu; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-11)
      <p>In photosynthesis, carbon dioxide is used as the carbon source; indeed, most carbon atoms in the structure of a massive tree—the trunk, the branches, the leaves—originate from CO2. This insight has profound implications for chemical synthesis: complex molecular structures are built from something as simple and inert as CO<sub>2</sub>. Scientists have long been fascinated by this concept, and ...
    • The origin dependence of the material constants: the permittivity and the inverse permeability 

      Anelli, Marco; Jonsson, Dan Johan; Fliegl, Heike; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-05-26)
      New derivations of origin-independent expressions for the electric permittivity are presented, starting either from the response function of the current density that defines the absorption coefficient, or from the off-resonance single-photon scattering amplitude that leads to the Kramers–Heisenberg dispersion formula. The resulting expression for the permittivity is compared with earlier work ...
    • Origin of Dual-Peak Phosphorescence and Ultralong Lifetime of 4,6-Diethoxy-2-carbazolyl-1,3,5-triazine 

      Paul, Lopa; Chakrabarti, Swapan; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-03-02)
      Recently, ultralong phosphorescence lifetime has been observed in 4,6-diethoxy-2-carbazolyl-1,3,5-triazine, and H-aggregation induced stabilization of the T1 state was suggested as its source. The response theory calculations demonstrate that the Davydov stabilization of the T1 state of the dimer is marginal with respect to the monomer and the corresponding transition moments are virtually the same. ...
    • Origin-independent two-photon circular dichroism calculations in coupled cluster theory 

      Friese, Daniel Henrik; Hättig, Christof; Rizzo, Antonio (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-03)
      We present the first origin-independent approach for the treatment of two-photon circular dichroism (TPCD) using coupled cluster methods. The approach is assessed concerning its behavior on the choice of the basis set and different coupled cluster methods. We also provide a comparison of results from CC2 with those from density functional theory using the CAM-B3LYP functional. Concerning the basis ...
    • Osmium-nitrido corroles as NIR indicators for oxygen sensors and triplet sensitizers for organic upconversion and singlet oxygen generation 

      Borisov, Sergey M.; Alemayehu, Abraham; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-26)
      The photophysical properties of nitridoosmium(VI) corroles have been investigated. The complexes exhibit room temperature NIR phosphorescence (l<sub>max</sub> 779–795 nm). Long decay times (110–150 ms in solution and 136–183 ms in polystyrene) are responsible for efficient quenching of the emission by oxygen. All the complexes act as efficient sensitizers of singlet oxygen (quantum yields of ...
    • Our Cup of Tea: Sustainable Organometallic Chemistry 

      Obligacion, Jennifer V.; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-25)
      What makes organometallic chemistry sustainable, or at least could make it more sustainable? A practical concept that allows us to set deliverable sustainability goals is Istvan Horváth’s sustainable definition of sustainability: Resources including energy should be used at a rate at which they are replaced naturally and the generation of waste cannot be faster than the rate of their remediation. ...
    • OXA-48-Mediated Ceftazidime-Avibactam Resistance Is Associated with Evolutionary Trade-Offs 

      Fröhlich, Christopher; Sørum, Vidar; Thomassen, Ane Molden; Johnsen, Pål Jarle; Samuelsen, Ørjan (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-27)
      Infections due to carbapenemase-producing Gram-negative pathogens are associated with limited treatment options and consequently lead to increased mortality and morbidity. In response, combinations of existing β-lactams and novel β-lactamase inhibitors, such as ceftazidime-avibactam (CAZ-AVI), have been developed as alternative treatment options. To understand the development of resistance and ...
    • Palladium(0)-Catalyzed Cross-Couplings of 2-Bromophosphinine 

      Kostenko, Nataliya; Eriksson, Cecilia; Engqvist, Magnus; Villa Gonzalez, Susana; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-05-21)
      A new Negishi-type cross-coupling of 2-bromophosphinine has been developed. The new method expands the scope of palladium-catalyzed couplings to monobromophosphinines, which have been considered as poor substrates so far. Moreover, aryl-, alkenyl-, and alkynylzinc bromides were found to be effective coupling partners.
    • Pan genome and CRISPR analyses of the bacterial fish pathogen Moritella viscosa 

      Karlsen, Christian; Hjerde, Erik; Klemetsen, Terje; Willassen, Nils Peder (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-20)
      Background: Winter-ulcer Moritella viscosa infections continue to be a significant burden in Atlantic salmon (Salmo salar L.) farming. M. viscosa comprises two main clusters that differ in genetic variation and phenotypes including virulence. Horizontal gene transfer through acquisition and loss of mobile genetic elements (MGEs) is a major driving force of bacterial diversification. To gain insight ...
    • Parameter-Free Extended Edit Distance 

      Muhammad Fuad, Muhammad Marwan (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
      The edit distance is the most famous distance to compute the similarity between two strings of characters. The main drawback of the edit distance is that it is based on local procedures which reflect only a local view of similarity. To remedy this problem we presented in a previous work the extended edit distance, which adds a global view of similarity between two strings. However, the extended edit ...
    • På vei mot en kollegial tilnærming til undervisning – seminarundervisning og pedagogisk opplæring av stipendiater 

      Johansen, Greta Kristine; Beerepoot, Maarten (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-19)
      Seminarundervisning har en viktig rolle i realfagsundervisning i høyere utdanning. Læringsaktivitetene i seminarene samsvarer ofte godt med eksamensformen og dermed bidrar seminarundervisning betydelig til <i>constructive alignment</i> (Biggs, 1999) i et emne. Den viktige rollen seminarundervisning har står i sterk kontrast med den begrensede eller fraværende opplæring ...
    • PCMSolver: an Open-Source Library for Solvation Modeling 

      Di Remigio, Roberto; Steindal, Arnfinn Hykkerud; Mozgawa, Krzysztof; Weijo, Ville; Cao, Hui; Frediani, Luca (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-25)
      PCMSolver is an open‐source library for continuum electrostatic solvation. It can be combined with any quantum chemistry code and requires a minimal interface with the host program, greatly reducing programming effort. As input, PCMSolver needs only the molecular geometry to generate the cavity and the expectation value of the molecular electrostatic potential on the cavity surface. It then returns ...
    • The Perfluoro Cage Effect: A Search for Electron-Encapsulating Molecules 

      Ghosh, Abhik; Conradie, Jeanet (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-01-25)
      Quantum chemical calculations have for some time predicted that perfluorinated polyhedral organic molecules should exhibit a low-energy LUMO consisting of the overlapping inward-pointing lobes of the C−F σ* orbitals. Accordingly, these molecules should be able to encapsulate an electron within the interior of their cavities. Inspired by the recent confirmation of this prediction for perfluorocubane, ...
    • Perturbed atoms in molecules and solids:the PATMOS model 

      Røeggen, Inge; Gao, Bin (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      A new computational method for electronic-structure studies of molecules and solids is presented. The key element in the new model – denoted the perturbed atoms in molecules and solids model – is the concept of a perturbed atom in a complex. The basic approximation of the new model is unrestricted Hartree Fock (UHF). The UHF orbitals are localized by the Edmiston-Ruedenberg procedure. The perturbed ...
    • Phase transfer catalyzed conjugate addition-initiated ring-closure (CAIRC) reactions with 2-bromo-2-cyclopentenones 

      Yirsaw, Alemayehu Mekonnen; carlson, Rolf (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-07)
      When 2-bromo-2-cyclopentenone is treated with various carbon nucleophiles containing active methylenes, it undergoes a conjugate addition initiated-ring closure (CAIRC) reaction. This leads to the formation of carboand heterocyclic compounds in a regioselective fashion with good to high yield. Several bases and phase transfer catalysts were investigated. CsF-Si(OEt)4 as base together with ...