Study of clusters of interest for liquid ionic alloys

Calculations are reported of the total energies and related quantities of sequences of small clusters of the form A(m)Pb(n), 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 A(4)Pb and A(4)Pb(4) 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.