Li3 Cluster Research Articles

Comparison Between Electride Characteristics of Li3@B40 and Li3@C60.

Density functional theory (DFT) based computation is performed on the endohedrally encapsulated Li3 cluster inside the B40 and C60 cages namely, Li3@B40 and Li3@C60. For both these systems, the Li-Li bond lengths are shorter than that in the free Li3 cluster. Due to confinement, the Li-Li vibrational frequencies increase in both the systems as compared to that in the free Li3 cluster. Thermodynamically, the formation of these two systems is spontaneous in nature as predicted by the negative values of Gibbs’ free energy changes (ΔG). For both the systems one non-nuclear attractor (NNA) is present on the middle of the Li3 cluster which is predicted and confirmed by the electron density analysis. The NNA population and the percentage localization of electron density at the NNA of the Li3@C60 system are higher than that in the Li3@B40 system. At the NNA the values of the Laplacian of electron density are negative and an electron localization function basin is present at the center of the Li3 cluster for localized electrons. Both systems show large values of nonlinear optical properties (NLO). Both the Li3 encapsulated endohedral systems behave as electrides. Electrides have low work function and hence have a great potential in catalytic activity toward the activation of small molecules (such as CO2, N2). Even some electrides have greater catalytic activity than some well-studied metal-loaded catalysts. As the systems under study behave as electrides, they have the power to show catalytic activity and can be used in catalyzing the activation of small molecules.

Theoretical study of boron, beryllium and lithium clusters (n=2–6), adsorption on graphitic carbon nitride and the study of acceptor-donor orbital of the coordination of a styrene molecule on [cluster/g-C3N4] systems

The adsorption of boron, beryllium and lithium clusters on graphitic carbon nitride g-C3N4, and the adsorption of styrene molecule on the B, Be, Li cluster/g-C3N4 sheet have been investigated through the density functional theory (DFT) calculations. Our calculations show distortion of the geometry of the clusters when coordinating with the g-C3N4 sheet. Boron (n = 5 and 6), beryllium (n = 2–4, 6) and Li3 cluster on g-C3N4 present characteristics to adsorb a styrene molecule. The styrene on Be4/g-C3N4 system exhibits better adsorption, due to the beryllium atoms have strong interactions with the π-orbitals of the aromatic ring of the styrene molecule. The study of natural bond orbitals of styrene-cluster/g-C3N4 systems showed the donation process from the styrene molecule and the g-C3N4 sheet towards the boron, beryllium and lithium clusters. Only back donation was observed the boron and beryllium clusters.

First-principles study of the electronic structure and transport properties of armchair graphene nanoribbons with adsorbed super-halogen LiF2 and super-alkali Li3 clusters

The electronic structure and quantum transport properties of pristine armchair graphene nanoribbons (AGNRs) and AGNRs adsorbing super-halogen LiF2 and super-alkaline Li3 clusters (Li3/AGNRs/LiF2) were investigated using density functional theory and non-equilibrium Green's function calculations. It was found that LiF2 and Li3 clusters are stably adsorbed on the AGNRs, and the adsorption of Li3 and LiF2 endows AGNRs with the characteristics of n-type and p-type semiconductors, respectively. The Li3/AGNRs/LiF2 structure reduces the band gap and the turn-on voltage, and improves the transmission coefficient of the ANGRs device. This structure also exhibit the rectification characteristics of a pn junction with the forward bias current greater than the reverse bias current. This shows that adsorption of super-alkali and super-halogen clusters in different regions of AGNRs is a feasible approach for obtaining AGNRs with pn junction characteristics.

Quantum Monte Carlo simulation for the many-body decomposition of the interaction energy and electron correlation of small superalkali lithium clusters.

Using the fixed-node diffusion Monte Carlo (FN-DMC) method, we calculate the total energy of small lithium clusters Lin (n = 2-6) to obtain the many-body decomposition of the interaction energy of 2- up to 6-body interactions. The obtained many-body decomposition of the interaction energy shows an alternating series with even and odd terms of attractive and repulsive contributions, respectively. The two-body attractive interactions guarantee the stability of the Li2, Li3, and Li4 clusters. For larger clusters Li5 and Li6, the 4-body attractive interactions are required for their stabilization once the strength of the 3-body repulsive interactions overwhelms that of the 2-body attractive ones. With increasing the cluster size, the additive and nonadditive contributions to the interaction energy increase linearly in magnitude but with different slopes for the two-dimensional (2D) planar and three-dimensional (3D) cagelike clusters. The significant increment in nonadditive effects from the 4-atom to the 5-atom cluster has driven the structural transition from 2D to 3D. Combining the FN-DMC calculations with the Hartree-Fock many-body decomposition of the interaction energy, we extract the correlation effects, showing that an odd-even competition pattern in the many-body repulsive and attractive interactions is crucial for the stabilization of the clusters.

Engineering Redox Potential of Lithium Clusters for Electrode Material in Lithium-Ion Batteries

Low negative electrode potential and high reactivity makes lithium (Li) ideal candidate for obtaining highest possible energy density among other materials. In this work we show a novel route with which the overall electrode potential could significantly be enhanced through selection of cluster size. Using first principles density functional theory and continuum dielectric model, we studied free energy and redox potential as well as investigated relative stability of Lin (n ≤ 8) clusters in both gas phase and solution. We found that Li3 has the lowest negative redox potential (thereby highest overall electrode potential) suggesting that cluster based approach could provide a novel way of engineering the next generation battery technology. The microscopic origin of Li3 cluster’s superior performance is related to two major factors: gas phase ionization and difference between solvation free energy for neutral and positive ion. Taken together, the present study provides insight into the engineering of redox potential in battery and could stimulate further work in this direction.

Theoretical studies of the global minima and polarizabilities of small lithium clusters

Lithium clusters Lin (n=1⿿20) have been investigated with density functional theory (DFT) and coupled-cluster (CC) methods. The global minima are located via an improved basin-hopping algorithm. Simulated polarizabilities are in good agreement with the measured data generally. The simulated polarizabilities for Li6, Li12 and Li19 are in reasonable agreement when thermal effects are included, except the Li3 cluster. A linear correlation for the inverse relationship between the CCSD calculated polarizabilities and ionization potential (IP) has been reported to have the linear coefficient of 0.996, which further strengthens our simulations.

Gerhard Ertl and His Research with Surface Science

Lithium clusters Lin (n = 1⿿20) have been investigated with density functional theory (DFT) and coupled-cluster (CC) methods. The global minima are located via an improved basin-hopping algorithm. Simulated polarizabilities are in good agreement with the measured data generally. The simulated polarizabilities for Li6, Li12 and Li19 are in reasonable agreement when thermal effects are included, except the Li3 cluster. A linear correlation for the inverse relationship between the CCSD calculated polarizabilities and ionization potential (IP) has been reported to have the linear coefficient of 0.996, which further strengthens our simulations.

Formation Mechanism and Binding Energy for EquilateralTriangle Structure of Li3 Cluster**The projectsupported by National Natural Science Foundation of China under Grant No. 19974027

The formation mechanism for the equilateral trianglestructure of Li3 cluster is proposed. The curve of the total energyversus the interatomic distance for this structure has been calculated byusing the method of Gou's Modified Arrangement Channel QuantumMechanics. The result shows that the curve has a minimal energy of-22.338 60 a.u at R = 5.82 a0. The total energy of Li3 when Rapproaches ∞ has the value of -22.284 09 a.u. This is alsothe total energy of three lithium atoms dissociated from Li3.The difference value of 0.0545 08 a.u. for the above two energy valuesis the dissociation energy of Li3 cluster, which is also itsbinding energy. Therefore the binding energy per lithium atom forLi3 is 0.018 169 a.u. = 0.494 eV, which isgreater than the binding energy of 0.453 eV per atom for Li2 calculatedin a previous work. This means that the Li3 cluster may be formed inthe equilateral triangle structure of side length R = 5.82 a0stably with a stronger binding from the symmetrical interaction amongthe three lithium atoms.

NMR Study of Lithium Dynamics and Molecular Motions in a Diethylamine−Molybdenum Disulfide Intercalation Compound

Measurements of the 13C, 7Li, and 1H nuclear magnetic resonance (NMR) of the nanocomposite formed by the intercalation of lithium and diethylamine in molybdenum disulfide, Li0.1MoS2[(C2H5)2NH]0.2, are reported. The strong Li−Li dipolar interaction strength, calculated from the 7Li NMR decoupling data, suggests the formation of lithium clusters. The dimensional restriction of the available space between the host layers supports a hypothesis that is based on the formation of Li3 clusters stabilized by amine ligands. The lithium relaxation is mainly due to the interaction between the quadrupolar moment of the 7Li nuclei and the fluctuating electric field gradient at the site of the nucleus, produced by the surrounding charge distribution. The dynamical parameters obtained from the 7Li temperature dependence of the spin−lattice relaxation indicate a high lithium mobility, which is attributed to the fast exchange motion of the lithium ions between the coordination sites within each Li3 aggregate. The 1H line s...

Nature of binding in small metal clusters

The ab initio many-body model potentials for the Li3 and Be3 clusters are constructed. Analysis of its exchange and dispersion contributions allows to elucidate the nature of binding in these clusters. The Li3 clusters are formed by the covalent chemical bonding, although the interstitial orbitals revealed in the spin-coupled studies of Gerratt and coauthors make the binding picture in the LiN clusters far enough from the convential covalent picture. The binding in the Be3 clusters has a mixed physical and chemical nature: it is provided by the additive van der Waals forces and the nonadditive three-body exchange forces. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 74: 241–247, 1999

Gaussian integral transforms of unconventional functions: contracted basis functions appropriate to molecules and metallic clusters

We report the development of new gaussian integral transforms one-electron functions. A straightforward recipe to generate gaussian contractions of these functions is introduced. The applications call into question the disseminated belief of the superiority of Slater type orbitals (STO) in molecular calculations. A first successful application of the Bessel K v (qr) function to a molecular system is presented. One of the integral transforms that yields the 0s function is used to generate contractions that have a better performance than the STO ones in cases that diffuse functions are needed. Applications are presented to some Li n clusters and a new conformation of the Li3 cluster is then proposed.

A configuration interaction study of small lithium clusters

A detailed study of Li2, Li3 and Li4 clusters is reported at the ab initio level. Fourteen different geometries of the clusters have been considered. The most stable geometrical forms at the Hartree-Fock configuration interaction level are found and compared with previously published theoretical and experimental results.

The CNDO/BW study of lithium clusters. I. Two‐, three‐, and four‐atomic clusters

AbstractThe CNDO/BW method is used for a detailed study of Li2, Li3, and Li4 clusters. The equilibrium distances between atoms, binding energies, ionization potentials, dipole moments, charges at atoms, and bond orders are investigated for 14 different geometries of the clusters. The most stable geometrical forms are found and compared with available theoretical and experimental results.