Structural, electronic and vibrational properties of PbnSn(n=1–9) clusters using density-functional theory

The density functional calculation with the generalized gradient approximation is applied to study the structural, electronic and vibrational properties of PbnSn clusters up to n=9n=9. It is found that ringlike structures are the lowest-energy configuration for n⩽3n⩽3. However, at the beginning of n=4n=4, three-dimensional spheroid structures are prevailed. The supercluster structures based on Pb2S2 and Pb3S3 bridges are dominant for the larger PbnSn with n⩾3n⩾3. In addition, we discussed the size dependence of binding energies, gaps between highest-occupied and lowest-unoccupied molecular orbitals, second-order difference of total energies, and the IR spectra of PbnSn clusters.