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Structural and electronic properties of PbnAgn (n=2-12) clusters were investigated by density functional theory with generalized gradient approximation at BLYP level in DMol3 program package. The optimized bimetallic PbnAgn (n=2-12) clusters were viewed as the initial structures, then, those were calculated by ab initio molecular dynamics (AIMD) to search possible global minimum energy structures of PbnAgn clusters, finally, the ground state structures of PbnAgn (n=2-12) clusters were achieved. According to the structural evolution of lowest energy structures, Ag atoms prefer gather in the central sites while Pb atoms prefer external positions in PbnAgn (n=2-12) clusters, which is in excellent agreement with experimental results from literature and the application in metallurgy. The average binding energies, HOMO-LUMO gaps, vertical ionization potentials, vertical electron affinities, chemical hardness η, HOMO orbits, LUMO orbits and density of states of PbnAgn (n=2-12) clusters were calculated. The results indicate that the values of HOMO-LUMO gaps, vertical ionization potentials, vertical electron affinities and chemical hardness η show obvious odd-even oscillations when n≤5, PbnAgn (n=2-12) clusters become less chemically stable and show insulator-to-metal transition with the variation of cluster size n, PbnAgn (n≥9) cluster are good candidates to study the properties of PbAg alloys. Those can be well explained by the density of states (DOS) distributions of Pb atoms and Ag atoms between-0.5 Ha and 0.25 Ha in PbnAgn (n=2-12) clusters. [ABSTRACT FROM AUTHOR]

The structural, relative stable and electronic properties of PbSn (n = 2-12) alloy clusters were systematically studied using density functional theory. The isomers of PbSn alloy clusters were generated and determined by ab initio molecular dynamics. By comparing the calculated parameters of Pb dimer and Sn dimers with the parameters from experiments, our calculations are reasonable. With the lowest-energy structures for PbSn clusters, the average binding energies, fragmentation energies, second- order energy differences, vertical ionization potentials, vertical electron affinities, HOMO-LUMO gaps, and density of states were calculated and analyzed. The results indicate that the Sn atoms have a tendency to bond together, the average binding energies tend to be stable up to n = 8, PbSn cluster is a good candidate to calculate the molecular interaction energy parameter in Wilson equation, the clusters become less chemical stable and show an insulator-to-metallic transition, 3, 6, 8 and 11 are magic numbers of PbSn (n = 2-12) clusters, the charges always transfer from Sn atoms to Pb atoms in PbSn clusters except for PbSn cluster, and density of states of PbSn clusters becoming continuous and shifting toward negative with the increasing size n. [ABSTRACT FROM AUTHOR]