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Open AccessArticle

Many-Body Effects in FeN4 Center Embedded in Graphene

1
Department of Physics, Northeastern University, Boston, MA 02115, USA
2
Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
3
Department of Physics, School of Engineering Science, LUT University, FI-53851 Lappeenranta, Finland
*
Author to whom correspondence should be addressed.
LUT University is the main affiliation of Bernardo Barbiellini.
Appl. Sci. 2020, 10(7), 2542; https://doi.org/10.3390/app10072542
Received: 28 January 2020 / Revised: 30 March 2020 / Accepted: 2 April 2020 / Published: 7 April 2020
We introduce a computational approach 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 generalized gradient approximation (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 affect the binding of ligands greatly. View Full-Text
Keywords: DFT and beyond DFT methods; density matrix renormalization group; electronic correlations and degenerate ground states; porphyrins; transition metals; graphene DFT and beyond DFT methods; density matrix renormalization group; electronic correlations and degenerate ground states; porphyrins; transition metals; graphene
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MDPI and ACS Style

Allerdt, A.; Hafiz, H.; Barbiellini, B.; Bansil, A.; Feiguin, A.E. Many-Body Effects in FeN4 Center Embedded in Graphene. Appl. Sci. 2020, 10, 2542. https://doi.org/10.3390/app10072542

AMA Style

Allerdt A, Hafiz H, Barbiellini B, Bansil A, Feiguin AE. Many-Body Effects in FeN4 Center Embedded in Graphene. Applied Sciences. 2020; 10(7):2542. https://doi.org/10.3390/app10072542

Chicago/Turabian Style

Allerdt, Andrew; Hafiz, Hasnain; Barbiellini, Bernardo; Bansil, Arun; Feiguin, Adrian E. 2020. "Many-Body Effects in FeN4 Center Embedded in Graphene" Appl. Sci. 10, no. 7: 2542. https://doi.org/10.3390/app10072542

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