Density functional theory study of binding energies, 7Li nuclear magnetic shielding, and electric field gradient tensors on the small clusters of LinHm (m≤n≤4)

The binding energies, geometries, Li-7 magnetic shielding, and electric field gradient tensors of hydrogenated lithium clusters, LinHm (m <= n <= 4), were studied via density functional theory approach. We optimized the structures using B3LYP functional and 6-311++G (2d,2p) basis set. The calculated binding energies of lithium hydride clusters indicate that hydrogenation energy of LinHm clusters decreases as the number of hydrogen atoms within the cluster increases. Our calculations also showed that for n = 4 clusters, the three-dimensional structure is more stable than the planar one. The study of the trends in the Li-7 magnetic shielding isotropy, sigma(iso), and anisotropies, Delta sigma, values are explained in terms of the interplay between the electronic and geometrical effects. The variations in the Li-7 nuclear quadrupole coupling constants, chi, and their associated asymmetry parameters, eta(Q), for different isomers of the lithium hydride clusters and the influence of hydrogenation on the EFG tensors are also discussed. For n = 4, we obtained a noticeable difference in the chi value from the planar to the three-dimensional structures. The atoms in molecules (AIM) analysis at the Li-H bond critical point reveals remarkably different topographical properties of the charge density and associated Laplacian fields for the planar and three-dimensional lithium hydride clusters.