Applications, molecular electronics active elements

It is beyond the scope of this chapter to discuss the range of structure-based methods that chemists can use for molecular afignment. This field of research has been, and continues to be, very active. One algorithm, called TGSA, will be presented here in some detail, however, because of its popularity in molecular quantum similarity studies. Structure-based techniques differ from the aforementioned techniques in several respects. First, they not attempt to maximize the MQSM for a pair of molecules. Second, they do not make a specific reference to molecular quantum similarity as such, they are aimed at a wider range of applications. Third, they are not based on electron density in a formal way, but instead they take a more familiar approach based on chemical topology. Consequently, they apply well-known concepts such as chemical bonds and try to overlap the most similar and largest common structure elements in both molecules. 

---