The magnetic binary lithium clusters W₂Li_n (n = 15‐19): A theoretical prediction of “di‐superatomic molecules”

Abstract

Based on the super valence bond (SVB) model, a motif of face-sharing bitetrahexahedral superatomic molecules M 1 M 2 @Li 20 (M 1 /M 2 = Ti and W) was recently constructed by fusion of two tetrahexahedral superatoms Ti@Li 14 and W@Li 14. Here, as an extension of the formation of molecules from superatoms, binary lithium clusters W 2 Li n (n = 14-19) are studied in conjunction with particle swarm optimization algorithm search and density functional theory calculations. The lowest-lying isomers of W 2 Li n (n = 15-19) with the magnetic moments of 0 to 3 μ B are identified as superatomic molecules by analysis of their molecular orbitals and chemical bonding patterns, whereas the global minimum isomer of W 2 Li 14 does not possess the geometric structure of monomer. Via a lithium atom sequentially removed, a series of superatomic bond orders of 3, 3.5, 4, and 4.5 are exposed, reminiscent of classical chemical bonds. Meanwhile, many isosupermolecules are found in the low-energy structures, predicting the diversity assembly of superatom materials. Our results highlight the tremendous opportunities for molecules assembled by superatoms, which may be in favor of the designs of nanoparticles or functional materials in future according to the SVB model.

Magnetic superatoms in cage doped 13-atom trimetallic Mg n Li12− n Sc (n = 1–8) clusters and their assembled discrete supermolecules: a theoretical prediction

“…There exists a couple of strategies to form the cluster assemblies in terms of the fusion motifs, which are found with a vertex shared, a face shared or the nonsharing structures. Considering the previous results of W 2 Li n (n = 15-19), where a five-membered Li ring shared between the two cluster units widespreadly appears in the low-lying isomers with less than 20 atoms [38], here the five-membered face-sharing motif is also adopted for the assembly of the discrete supermolecules. Further taking the assembled systems possessing four magnesium atoms as an example, 12 low-lying isomers of Mg 4 Li 13 Sc 2 are displayed in figure 5(A), of which frequency calculations give no imaginary values, and these low-lying geometric structures can be remained during MD simulations at 300 K (figure 3), confirming that they are local minima.…”