Theoretical Study of Small (NaI)_n Clusters

Abstract

A systematic theoretical study of stoichiometric clusters (N aI) n up to n = 15 is performed using the ab initio Perturbed-Ion (PI) model. The structures obtained are compared to previous pair potential results, and observed differences between (N aI) n clusters and previous ab initio results for other alkali halide clusters are discussed. (N aI) n clusters with n up to 15 do not show yet a marked preference for geometries which are fragments of the bulk lattice. Instead, stacks of hexagonal rings or more open structures are obtained as ground structures in clusters with n = 3, 6, 7, 9, 10, 12, 13 and 15, indicating that convergence to bulk structure is not achieved yet at this size range. Low lying isomers which are fragments of the crystal lattice exist, nevertheless, for those cases. The binding energies show that clusters with n = (4), 6, 9 and 12 molecules are specially stable. The binding energy has been decomposed in contributions which allow for an intuitive interpretation. Some electronic properties like ionization potentials and electronic energy levels are also studied.

Structures and stabilities of doubly charged (MgO)nMg2+ (n=1–29) cluster ions

“…Both sets of calculations predict the clusters with nϭ4, 8,11,13,16,19,22,25, and 27 to be especially stable, a result that is in complete agreement with the experimental enhanced abundances reported by Ziemann and Castleman. 19 The interpretation of the enhanced stabilities in terms of highly compact fragments of a face-centered cubic crystalline lattice is not appropriate for such small clusters.…”

“…3. Minima are apparent at nϭ4, 8,11,13,16,19,22,25, and 27. Thus, the experimental results concerning enhanced relative stabilities are properly reproduced by our calculations.…”

“…[24][25][26][27][28] Its theoretical foundation lies in the theory of electronic separability, 33,34 and its practical implementation in the Hartree-Fock ͑HF͒ version of the theory of electronic separability. 21,22 The HF equations of the cluster are solved stepwise, by breaking the cluster wave function into local group functions ͑ionic in nature, in our case͒.…”

“…[29][30][31] The rest of the paper is organized as follows: in Sec. II we give a brief resume of the aiPI model as applied to clusters ͑full expositions of the method have been given elsewhere 24,25 ͒, a comparison with pair potential models which serves to assert the quality of the methodology, and the details of the computational procedure. The results are presented in Sec.…”

Structural stabilities and electronic properties of Mg28-nAln clusters: A first-principles study

“…Probing the ground state structures of bimetallic clusters is more complex than the corresponding pure clusters, due to the existence of homotops 26 which have the same number of total atoms, component and geometrical structures, but different in the atom arrangement. 5 With the increasing of the bimetallic cluster size, the number of homotops increases rapidly.…”