Study of clusters of interest for liquid ionic alloys

Abstract

Calculations are reported of the total energies and related quantities of sequences of small clusters of the form A,,,Pb,, where A is an alkali atom, n < 6 and m < 9. The object of this study is to shed light on the stoichiometry and the possible formation of complexes in A-Pb liquid alloys. The calculations are performed using empty core pseudopotentials and the spherical average approximation for the cluster. The results are insensitive to the choice of alkali atom apart from a smooth trend with the progression from Li to Cs. The calculated total energies suggest that clusters with compositions A4Pb and A4Pb4 are very stable against a change in the number of Pb or A atoms and support the possibility of these clusters forming in the liquid alloys. This stability arises from an electronic shell-closing effect.

Transition Metal Doped Aluminum Clusters: An Account of Spin

“…Several other factors like the bulk state miscibility or the radius ratio of constituent atoms for close packing also play a key role in determining the atomic organization within the cluster. 15,17 Aside from the inter−atomic distances smooth trends are also observed in other properties as well. HOMO−LUMO gap of Al 5 M series (Figure 6b) shows a steady increase up to Al 5 Cr then following a sudden drop at Al 5 Mn it again increases up to Al 5 Co and finally converges with the plot of HOMO−LUMO gap of low spin clusters (Al 5 Ni−Al 5 Zn).…”

“…Explanation of this phenomenon can be given by invoking the fact that in binary metal clusters the atomic volume of individual element is not the only factor that controls the interatomic distances within the clusters. Several other factors like the bulk state miscibility or the radius ratio of constituent atoms for close packing also play a key role in determining the atomic organization within the cluster. , …”

“…For example, immiscibility in the bulk state may also be reflected within the intermolecular distances of heteroatomic clusters. 17 Some bimetallic clusters even show indication of atomic ordering like phase separation, very similar to their bulk counterparts. 15 A brief survey on these properties by theoretical means (e.g., chemical order parameters) 18,19 fruitful to answer long lasting questions on growth and form of the bulk matter itself.…”

“…Inclusion of additional impurities can be sufficed to perturb the order of jellium shells, resulting in different sets of magic numbers and thereby alternating the reactivity trends, ionization energies, and other related properties for the whole set of clusters. , All these phenomena provide new challenges and an excellent opportunity to develop new models and also modify an existing one which will eventually be able to predict and explain such observations. − Aside from these, clusters with impurities can further be considered as microanalogues of bulk metals; hence, they can provide a substantial amount of information about the bulk state of the corresponding material. For example, immiscibility in the bulk state may also be reflected within the intermolecular distances of heteroatomic clusters . Some bimetallic clusters even show indication of atomic ordering like phase separation, very similar to their bulk counterparts .…”