Comparison of group 14 elements in sp³ and sp² environment by fragment structure energy analysis

To explore the characteristics of group 14 elements in sp³ and sp² hybrid environments systematically, the concept of fragment structure energy (FSE) was proposed through ab initio molecular orbital method. A fragment in this study means a building block of molecular structure and the energy of each kind of fragments (FSE) is obtained from the total electronic energy of different size of model compounds by just a simple algebraic method. The model compounds are the hydrogen-terminated diamond and graphene analogs as the typical compounds in the ideal sp³ - and sp² -environment, respectively. As a result, the sp³ environment was found to be more stable than the sp² for all the group 14 elements (C-Pb) in the ideal hybrid environment. Furthermore, a mixing effect of carbon and heavier group 14 elements (E = Si, Ge, Sn, and Pb) was investigated by comparing the E/C-alternately mixed- and the pure FSEs.