Tin content effect on the structural and energetic properties of lead telluride clusters

Abstract

Density functional theory calculations are performed to investigate tin content effect on the structural and energetic properties of lead telluride clusters. Tin atoms prefer to be doped on the exterior sites rather than the interior sites of lead telluride clusters. The geometry of the clusters is not affected due to the amount of tin content except for a slight distortion observed by changes in bond length. A considerable change has been observed in the HOMO–LUMO gap of the clusters with increasing number of tin atoms for corresponding size, but the band inversion which is observed in the bulk is not observed on the clusters in these size ranges. The change in binding energy between doped clusters is almost negligible for the same number of tellurium atoms, it is observed to be constant or there is a change of up to 0.02 eV with each successive doping of tin atoms. Both adiabatic and vertical detachment energies are observed to increase with increasing number of doping tin atoms. The fragmentation energy of losing PbTe dimer changes with an even–odd alternation, clusters with even number of Te atoms are more stable because they need higher energy to dissociate as compared to the other clusters. Some clusters are found to be magic (more stable) because of their enhanced binding, HOMO–LUMO gap, and fragmentation energies, typical examples are Pb4−mSnmTe4 (m = 1–4) clusters.