Endohedral small metallofullerenes as a basis for the formation of heterostructures

The study of heterostructures with specific physico-chemical properties useful for the needs of nanoelectronics, microsystems engineering and other branches of nanotechnology is important and relevant. A separate class of chemical compounds in a number of such materials are structures that include various modifications of carbon nanoobjects. One of the most popular nanostructures are fullerenes, the study of which was started at the end of the XX century and continues to the present day. Now the attention of researchers is focused on fullerenes with a small diameter, the composition of which is described by the formulas C$_{20}$, C$_{24}$, C$_{28}$. It is known that the presence of a cavity in fullerenes makes it possible to intercalate them with atoms and even small molecules. Endohedral complexes of fullerenes with alkali (Li, Na, K) and transition (Ti, Zn) metals were considered. The study was carried out using quantum chemical modeling methods within the framework of density functional theory in the B3LYP variant using the basic sets 6-311++G(d,p) and cc-pVDZ. We obtained optimized structures of endohedral fullerenes M@C$_{{20},{24},{28}}$ (M = Li, Na, K), as well as Zn@C$_{28}$ and Ti@C$_{28}$, and calculated the values of the energy gap of each complex. Based on this, it was concluded that it is possible to form heterostructures based on some of these materials.