Electronic and stability characters of endohedral Zn@Sin and exohedral SinHn (n=20, 30, 40, 50, 60) fullerenes: A DFT approach

By performing DFT calculations, the structural and electronic properties of Si-n, endohedral Zn@Si-n and hydrogenated SinHn fullerenes are investigated. Our calculations indicate that the most stable structure is related to the Si-40 fullerene and the energy gap of investigated Si-n cages is in the range of 0.18 - 0.65 eV. Furthermore, the calculated values of embedding energies show that endohedral doping method has the most effect on the stability of Si-20 cage as the encapsulation of Zn metal atom is very successful method in stabilizing small Si-20 fullerene. Electronic structure analysis indicates that the energy gap of Zn@Si-20 cage is raised to the higher value which means the reactivity of new structure is decreased. In continue the stability of hydrogenated SinHn cages is also considered. On the basis of geometry optimization, the most stable structure is belonging to Si20H20 cage and the calculated binding energy of these structures are predicted in the order Si20H20 > Si60H60 > Si50H50 > Si30H30 > Si40H40 In comparison, the energy gap of SinHn cages is found to be larger than the energy gap of Sin and Zn@Sin cages. In conclusion, the exohedral hydrogen doping method is much better than the endohedral metal doping for stabilizing Si-n cages through increasing thermodynamic and kinetic stability. (C) 2016 Elsevier B.V. All rights reserved.