{
  "id": "1906.05236",
  "version": "v1",
  "published": "2019-06-12T16:11:54.000Z",
  "updated": "2019-06-12T16:11:54.000Z",
  "title": "Many-body effects in porphyrin-like transition metal complexes embedded in graphene",
  "authors": [
    "Andrew Allerdt",
    "Hasnain Hafiz",
    "Bernardo Barbiellini",
    "Arun Bansil",
    "Adrian E. Feiguin"
  ],
  "categories": [
    "cond-mat.mes-hall"
  ],
  "abstract": "We introduce a new computational method to study porphyrin-like transition metal complexes, bridging density functional theory and exact many-body techniques, such as the density matrix renormalization group (DMRG). We first derive a multi-orbital Anderson impurity Hamiltonian starting from first principles considerations that qualitatively reproduce GGA+U results when ignoring inter-orbital Coulomb repulsion $U'$ and Hund exchange $J$. An exact canonical transformation is used to reduce the dimensionality of the problem and make it amenable to DMRG calculations, including all many-body terms (both intra, and inter-orbital), which are treated in a numerically exact way. We apply this technique to FeN$_4$ centers in graphene and show that the inclusion of these terms has dramatic effects: as the iron orbitals become single occupied due to the Coulomb repulsion, the inter-orbital interaction further reduces the occupation yielding a non-monotonic behavior of the magnetic moment as a function of the interactions, with maximum polarization only in a small window at intermediate values of the parameters. Furthermore, $U'$ changes the relative position of the peaks in the density of states, particularly on the iron $d_{z^2}$ orbital, which is expected to greatly affect the binding of ligands.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2019-06-12T16:11:54.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "many-body effects",
      "anderson impurity hamiltonian starting",
      "study porphyrin-like transition metal complexes",
      "coulomb repulsion",
      "multi-orbital anderson impurity hamiltonian"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}