The role of TM’s (M’s) d valence electrons in TM@X12 and M@X12 clusters

Abstract

Using the density functional theory method, the icosahedral TM@X12 (M@X12) clusters (TM=Mn, Tc, Re; M=Zn, Cd, Hg; and X=Sn, Ge), which are composed of Sn12 (Ge12) shell covering a single TM (M) atom, have been systematically examined to explore the role of TM’s (M’s) d valence electrons playing in the clusters. The results show that the magnetism originate from the contribution of TM’s d valence electrons to TM@X12 clusters, where TM’s (M’s) d valence electrons are not included in the superatomic electronic states to TM@X12 (M@X12) clusters. Taking into account the structural stability (imaginary frequency, binding energy, embedding energy, and core-shell interaction) as well as the chemical stability (HOMO-LUMO gap) after, we proposed that TM@X12 and M@X12 clusters can be assigned as the protyle superatoms. Furthermore, the results suggest that M@C60 clusters can not be superatoms, because their negative embedding energies and the distance from the center atom (M) to C atom is larger than the sum of their Van Waals radii. Interestingly enough, we may obtain a simple judging method: for a magnetic superatom, the smaller the energy gap between the highest occupied magnetic state (HOMS) and Fermi level or HOMO (MOgap, or MFgap), the easier on the change of its spin magnetic moment.

Exploring the structural stability order and electronic properties of transition metal M@Ge12 (M = Co, Pd, Tc, and Zr) doped germanium cage clusters

“…All the related parameters are shown in table 2. The outcomes gained by the B3LYP functional with LANL2DZ ECP basis set are acceptable as it is in good agreement with reported theoretical and experimental results [1][2][3][4][44][45][46][47][48][49]…”

Endohedrally Doped Cage Clusters

“…In particular, all the theoretical studies predicted that Mn@Sn 12 possesses a large magnetic moment of 5 μ B 67,528,590,618−620 , which was confirmed by experiment (5.3 ± 1.2 μ B ). 607 Note that Mn@Sn 12 also has a moderate HOMO−LUMO gap of about 1.1 eV and a reasonable embedding energy (up to 6.89 eV), 590 making it a stable magnetic superatom 67 as a building block of spintronic devices and magnetic nanomaterials.…”

“…The [618] MPWB1K/SKBJ 3.03 5 Mn@Sn 12 [619] PW91/planewave 3.05 1.12 5 Ti@Sn 12 [620] BLYP/DNP 0.57 2.55 4.47 2 V@Sn 12 [620] BLYP/DNP 0.58 2.57 4.78 3 Cr@Sn 12 [620] BLYP/DNP 0.05 2.41 3.35 4 Mn@Sn 12 [620] BLYP/DNP 1.08 2.43 3.59 5 Fe@Sn 12 [620] BLYP/DNP 0.20 2.52 4.01 4 Co@Sn 12 [620] BLYP/DNP 0.43 2.58 4. 35 3 Ni@Sn 12 [620] BLYP/DNP 0.22 2.59 4.11 2 Pu@Sn 12 [621] B3LYP/TZVP 3.22 1.97 2.01 0 Zn@Sn 12 [615] B3LYP/LanL2DZ 2.74 2.50 2.12 0 Mn@Sn 12 [590] BPW91/LanL2DZ 3.08 1.08 2.64 6.89 5 Tc@Sn 12 [590] BPW91/LanL2DZ 3.05 0.54 2.75 9.17 5 Re@Sn 12 [590] BPW91/LanL2DZ (b) Molecular orbital energy levels (in eV) of Zn@Sn 12 and Mn@Sn 12 , where the superatomic orbitals corresponding to different spherical harmonics (angular momentum) have been indicated. Black lines and blue lines represent the occupied levels and the unoccupied levels, respectively.…”

“…In the literature, many ab initio calculations have been reported on the atomic structures, energetic stabilities, and electronic properties of endohedrally doped M@Ge n clusters in both neutral and charged states, ,,,,,,,,,− which are summarized in Table . Generally speaking, the smallest cage that can accommodate a metal atom is Ge 8 .…”

“…So far, most previous theoretical studies focused on endohedrally doped M@Sn 12 cage clusters, ,,,− and the main results are summarized in Table . All these M@Sn 12 clusters prefer a nearly perfect icosahedral cage configuration with only small distortion, while the other possible cage isomers such as cuboctahedron are less stable .…”