Theoretical Study of Mixed Silicon−Lithium Clusters SinLip(+) (n = 1−6, p = 1−2)

Exploring the Structure, Energetic, and Magnetic Properties of Neutral Small Lithium Clusters Doped with Yttrium: Supermagnetic Atom Research

Density functional theory calculations based on magnetic and energetic stability criteria were performed to study a series of yttrium-doped lithium neutral clusters. A relativistic approximation was employed to properly describe the energy and multiplicity of the given clusters' fundamental states. The interaction of the 4d-Y atomic orbitals with the sp-Li states had an important role in the magnetic and energetic behavior of the selected systems. The spin density was concentrated over the yttrium atom regardless of the size of the cluster. Li7Y is a new stable superatom due to its enhanced magnetic properties.

Structure and stability of small lithium-chloride LinClm(0,1+) (n ≥ m, n = 1–6, m = 1–3) clusters

Detailed theoretical investigations along with the experimental observations of new small chlorine-doped lithium clusters are presented.

A template for a planar tetracoordinate heavier group 14 atom: a global study of C2Si2X(q) (X = C, Si, Ge, Sn, Pb; q = +1, 0, -1)

Through a global isomeric study, we computationally identified the first structural template C2Si2X that could encompass a planar tetracoordinate X for all the heavier group 14 elements X in the 0, +1 or -1 charge state. We thus significantly expanded the traditional 16/17/18ve rules to 19/20/21ve for ptX.

Tuning spin-states of carbynes and silylynes: a long jump with one leg

The challenge motivating this paper is to induce, by chemical substitution, a silylyne, SiR, or a congeneric carbyne, CR, to adopt the high-spin quartet rather than the low-spin doublet as its ground state. The difficulty is seen in the preference for the doublet of the parent SiH (doublet-quartet energy difference ∼39 kcal/mol, favoring the doublet) or CH (∼17 kcal/mol). Strategies for having high-spin ground state parallel those for silylenes and carbenes: greater electropositivity (σ-donation) and π-acceptance of the single substituent favor the high-spin state. The electronegativity trend can be understood from an ions in molecules way of thinking already present in the literature in the works of Boldyrev and Simons, and of Mavridis and Harrison; i.e., the quartet ground state spin of some CR/SiR species is largely determined by the ground state spin of C(-)/Si(-). In this study, we provide a diabatization analysis that solidly confirms the ions in molecules picture and explains the difference in the equilibrium internuclear distances for the two spin states. In general, electronegativity dominates the ordering of spin states. π-Acceptors also help to lower the quartet state energy of the many carbynes (silylynes) examined, whose range of doublet-quartet differences calculated is impressive, 120 (100) kcal/mol. The qualitative understanding gained leads to the prediction of some quartet-ground state carbynes (CMgH, CAlH2, CZnH, CSiH3, CSiF3, etc.) and a smaller number of silylynes (SiMgH, SiMgF, SiBeH, etc.). A beginning is made on the energetics of approach geometries of the fragments in the highly exoergic dimerization of CH to acetylene; it should proceed for the ground state doublet CH through C2h-like trajectories, with no activation energy.

Structure and electronic properties of alkali-C60 nanoclusters

I investigated the structural and electronic properties of both Na(n)C(60) and Li(n)C(60) (n < or = 12) clusters in the framework of density-functional theory. The behavior of the alkali atoms over the C(60) surface is analyzed. The hypotheses for either an homogeneous coating of the C(60) surface by the alkali atoms or the growth of an alkali droplet not wetting the fullerene surface are discussed. Lithium atoms are found to coat homogeneously the fullerene on the C(60) surface via pentagonal sites, contrary to sodium atoms, which prefer to form 4-atom islands on the surface. The charge transfer, the energetics, and the dipole moments are discussed in relation with available results. The adsorption of alkali atoms on the C(60) surface considerably enhances the capacity of C(60) to accept electrons. The arrangement of lithium atoms seems more favorable for the hydrogen storage than that of sodium atoms.