Theoretical study of the relative stability of Si8H8−nLin(n = 0–8) clusters: Investigating the roles of isoelectronic H and Li atoms

In this work, we report ab initio calculations, based on density functional (DFT) theory and second order Møllar–Plesset (MP2) perturbation methodology to investigate the relative stability of Si8H8−nLin(n = 0–8) clusters. The work presented in this paper is aimed at to investigate if lithium atoms are better candidates over hydrogen atoms to saturate the dangling bonds while stabilizing a three dimensional (3D) silicon cluster, such as S8, so that it can promote the same point group symmetry as in its carbon analog. Such a concept was first hypothesized by Zdetsis (J. Chem. Phys. 127 (2007) 214–306) while attempting benzene symmetry in Si6Li6 ring. The cubic Si8 cluster has been saturated both by H and Li atoms, and the sequential replacement of hydrogen by lithium atom is marked by the decrease in binding energy, HOMO–LUMO gap, ionization potential, and chemical hardness inferring that hydrogen atoms are preferable candidates over lithium atoms for the stabilization of 3D Si8 cluster. In addition, it is observed that both H and Li atoms, induce cubane symmetry (Oh) in 3D Si8 cluster provided that they undergo terminal bondings with Si atoms. On the other hand, Li atoms placed at the bridge sites are found to distort the structure of Si8 from the cubane symmetry.