Now showing items 1-8 of 8

  • Tellgren, Erik; Kvaal, Simen; Sagvolden, Espen; Ekström, Ulf Egil; Teale, Andrew Michael; Helgaker, Trygve (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2012)
    The selection of basic variables in current-density-functional theory and formal properties of the resulting formulations are critically examined. Focus is placed on the extent to which the Hohenberg-Kohn theorem, ...
  • Laestadius, Andre; Tellgren, Erik (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    Coupled cluster (CC) methods are among the most accurate methods in quantum chemistry. However, the standard CC linear response formulation is not gauge invariant, resulting in errors when modelling properties like optical ...
  • Tellgren, Erik; Kvaal, Simen; Helgaker, Trygve (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2014)
    The N-representability problem is the problem of determining whether there exists N-particle states with some prescribed property. Here we report an affirmative solution to the fermion N-representability problem when both ...
  • Laestadius, Andre; Penz, Markus; Tellgren, Erik; Ruggenthaler, Michael; Kvaal, Simen; Helgaker, Trygve (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2018)
    A detailed account of the Kohn–Sham (KS) algorithm from quantum chemistry, formulated rigorously in the very general setting of convex analysis on Banach spaces, is given here. Starting from a Levy–Lieb-type functional, ...
  • Penz, Markus; Laestadius, Andre; Tellgren, Erik; Ruggenthaler, Michael (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    The exact Kohn-Sham iteration of generalized density-functional theory in finite dimensions with a Moreau-Yosida regularized universal Lieb functional and an adaptive damping step is shown to converge to the correct ...
  • Sen, Sangita; Tellgren, Erik (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    We present a kinetic energy tensor that unifies a scalar kinetic energy density commonly used in meta-generalized gradient approximation functionals and the vorticity density that appears in paramagnetic current-density-functional ...
  • Reimann, Sarah; Borgoo, Alex; Tellgren, Erik; Teale, Andrew Michael; Helgaker, Trygve (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2017)
    We study the effects of magnetic fields in the context of magnetic field density-functional theory (BDFT), where the energy is a functional of the electron density ρ and the magnetic field B. We show that this approach is ...
  • Sen, Sangita; Tellgren, Erik (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    External non-uniform magnetic fields acting on molecules induce non-collinear spin densities and spin-symmetry breaking. This necessitates a general two-component Pauli spinor representation. In this paper, we report the ...