Blar i forfatter "Brakestad, Anders"

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    • Applications of Multiwavelets to Energies and Properties 

      Brakestad, Anders (Doctoral thesis; Doktorgradsavhandling, 2022-02-18)
      The goal of quantum chemistry is to provide fast and accurate algorithms for the computation of molecular energies and properties. Over the years, a large number of methods have become available, and today computational chemists have a very rich toolbox of protocols that can be used to gain insight to chemistry. Gaussian type orbital (GTO) basis sets are at the core of most modern algorithms, and ...

    • Multiwavelets applied to metal–ligand interactions: Energies free from basis set errors 

      Brakestad, Anders; Wind, Peter; Jensen, Stig Rune; Frediani, Luca; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-02)
      Transition metal-catalyzed reactions invariably include steps where ligands associate or dissociate. In order to obtain reliable energies for such reactions, sufficiently large basis sets need to be employed. In this paper, we have used high-precision multiwavelet calculations to compute the metal–ligand association energies for 27 transition metal complexes with common ligands, such as H2, CO, ...

    • Role of conical intersection seam topography in the chemiexcitation of 1,2-dioxetanes 

      Fdez. Galván, Ignacio; Brakestad, Anders; Vacher, Morgane (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-06)
      Chemiexcitation, the generation of electronic excited states by a thermal reaction initiated on the ground state, is an essential step in chemiluminescence, and it is mediated by the presence of a conical intersection that allows a nonadiabatic transition from ground state to excited state. Conical intersections classified as sloped favor chemiexcitation over ground state relaxation. The chemiexcitation ...

    • Scalar Relativistic Effects with Multiwavelets: Implementation and Benchmark 

      Brakestad, Anders; Jensen, Stig Rune; Tantardini, Christian; Pitteloud, Quentin Gregoire; Wind, Peter Ariaan; Užulis, Jānis; Gulans, Andris; Hopmann, Kathrin Helen; Frediani, Luca (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-01-05)
      The importance of relativistic effects in quantum chemistry is widely recognized, not only for heavier elements but throughout the periodic table. At the same time, relativistic effects are strongest in the nuclear region, where the description of electrons through a linear combination of atomic orbitals becomes more challenging. Furthermore, the choice of basis sets for heavier elements is ...

    • Static polarizabilities at the basis set limit: A benchmark of 124 species 

      Brakestad, Anders; Jensen, Stig Rune; Wind, Peter; D'Alessandro, Marco; Genovese, Luigi; Hopmann, Kathrin Helen; Frediani, Luca (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-16)
      Benchmarking molecular properties with Gaussian-type orbital (GTO) basis sets can be challenging, because one has to assume that the computed property is at the complete basis set (CBS) limit, without a robust measure of the error. Multiwavelet (MW) bases can be systematically improved with a controllable error, which eliminates the need for such assumptions. In this work, we have used MWs within ...