Effect of Coulomb repulsion on spin and orbital magnetism of cobalt–benzene complex: A relativistic density functional study

The effect of Hubbard-like interaction on molecular magnetism of TM-coronene complex (TM = Fe and Co)

“…Evidently, it can be concluded that both of the Fe-coronene and Co-coronene structures prefer a low-spin GGA-ground state. Our GGA results are in good agreement with the previous GGA-DFT studies for Co and Fe on benzene [6,7,9], graphene [7,20] and coronene [4,5]. However, XMCD measurements have revealed high-spin ground state for Fe and Co adatoms adsorbed on graphene [14,22].…”

“…The GGA-total energy diagram of Fe-coronene has a global minimum at 1.54 Å whereas for Co-coronene the global minimum is located at 1.56 Å. The equilibrium distances are in good agreement with other theoretical works [6,7,9,35,37]. The spin magnetic moment diagrams (red circles in figure 2) show that there are low-spin and high-spin configurations, as well as a transition region for both of Fe-coronene and Co-coronene complexes.…”

“…The metal-polyaromatic hydrocarbon (M-PAH) complexes are particularly interesting since PAHs are produced during combustion process, and the interaction of these molecules with metal atoms has been suggested as a likely source of unidentified infrared bands in the interstellar dust [1]. Moreover metal-organic complexes as building blocks of novel magnetic materials have been the focus of theoretical [1][2][3][4][5][6][7][8][9] and experimental [10][11][12][13][14][15] investigations. Coronene, C 24 H 12 , with six benzene rings fused to a central six-member ring, is the smallest polyaromatic hydrocarbon that locally resembles graphene.…”

“…Transition metal atoms embedded in a host structure gain degenerate and non-degenerate states with strong correlations among their valence electrons [17]. Moreover, electron intra-correlations significantly affect the electronic structure [18,19] and consequently the geometry of adsorption and magnetism of transition metal adatoms [3,6]. It is found that inclusion of a Hubbard-like Hamiltonian in electronic structure calculations such as in the GGA+U approach may promote the consistency of theoretical results with experiments, regarding spin states and strength of binding [20].…”

Magnetic 3d adatoms on free-standing and Ni(111)-supported graphene

“…In this section we briefly summarize the results on the adsorption of TM adatoms on the unsupported graphene monolayer, a topic that has been already addressed by DFT in several works in the last decade [8][9][10][11][12][13][14]. Such investigations have delved into the influence of the proposed methodology (LDA/GGA, LDA + U, Van der Waals corrections) on properties such as the preferred adsorption site, adsorption geometry, and ground-state electronic and spin configuration of the adatoms, The adatoms can be classified as physisorb or chemisorb on graphene depending on the adsorption energy and corresponding adatom-graphene distance [15,17,47,48]. Moreover, it has been shown that there is a correlation between the electronic configuration of the adatom and its distance from the substrate.…”