Are lithium hydride clusters purely ionic? Study using model potentials and density-functional theory

Abstract

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Structural Evolution and Stability of Hydrogenated Lin (n = 1–30) Clusters: A Density Functional Study

“…Analysis of the vibrational frequencies by Chen et al shows that with T d symmetry Li 4 H 4 has tetracentered bonding and is more rigid when compared to the tricentered bonded structure with D 4 h symmetry. The optimized geometry of Li 5 H 3 is a distorted cube with F-center vacancy and also has a tail of a Li atom attached to it; the same has been reported by Koutecky et al The optimized geometry of Li 5 H 4 is a distorted cube with a tail of a Li atom; a similar structure is found for its cationic counterpart, in contradiction to the structure reported by Bertolus et al For Li 5 H 5 we find a chair-type structure, and Li 6 H 4 has a caplike structure, in agreement with Koutecky et al…”

“…The exchange correlation functional, B3LYP, is a widely used hybrid functional comprised of Becke’s three-parameter exchange functional and the Lee–Yang–Parr correlation functional . It has been shown that B3LYP yields good results on structures and energetics of ion-covalent clusters and has been successfully employed to investigate the ground state geometries and electronic structure calculations of the Li n H m cluster. ,,, Hadipour et al have employed the B3LYP functional with 6-311G++(2d, 2p) basis set to predict geometries, binding energies, atomic charges,Li nuclear magnetic shielding, and EFG tensors of small Li n H m ( m ≤ n ≤ 4) clusters. The present work employs the B3LYP functional with 6-311G++(d, p) basis set; the double plus version in the basis set adds the diffuse function to the hydrogen and Li atom; and the p function is added for the H atom and d function for the Li atom.…”

“…Numerous papers ,,,, have been devoted to finding global minima of small Li n H m clusters. The present work does not attempt to find the lowest energy structure among the different isomers of Li n H m clusters.…”

“…Fuentealba et al have conducted DFT , based studies of Li n H m ( n ≤ 4, m ≤ 4) clusters with the focus on static dipole polarizability and electron localization function to analyze the bonding characteristic. Bertolus et al presented a study of Li n H n and Li n +1 H n + ( n up to 7) and Li 14 H 13 + using both DFT and Model Potential, and their results have shown that Li–H is almost totally ionic. Wu and Jones have presented a joint experimental/DFT study of the enthalpies of reaction for the hydrogenated Li clusters.…”