Electronic and geometric stability of double titanium-doped silicon clusters

Abstract

We performed the genetic algorithm (GA) incorporated with density functional theory (DFT) calculations to investigate the atomic and electronic properties of a series of Ti2Si n (n = 3 = –24) clusters. Comprehensive consideration on the formation energy, the second difference in cluster energy and the addition energy of Si to a Ti2Si n−1 cluster as well as the HOMO-LUMO gap, our results show that Ti2Si4 cluster is the most stable one in the series of clusters, followed by the Ti2Si13, Ti2Si21,Ti2Si15 and Ti2Si7 clusters, which can be understood by the combination of symmetry and electron shell filling rule. The silicon cage could be obviously enhanced by doping double Ti atoms making them promising nanoscale materials.