Theory Study On Typical Carbon Materials

Carbon materials from fullerene to graphene have unique properties and potential applications values. They can be used in the field of materials science, chemistry and physics. In recent years, they have attracted special interest for researchers and have demonstrated their unique charm. The properties of carbon materials can be influenced by adsorption of foreign atoms on graphene and the movement of metal atoms in fullerene. In this paper, we have investigated the interaction bttween X(X=H, F) and graphene and the motion of matal atoms inside La@C74and Eu@C82.Firstly, the adsorption mechanism of X(H、 F) on graphene C54H18CD6h was studied through DFT. With the aid of the representative patch of C54Hi8(D6h), we discussed the stable structure of C54H18-X(H、 F) and found that C54Hi8-H2and C54HJ8-F4are the most stable isomers in their own systems. In addition, the transition states, as well as reaction pathways of X(Hs F) transferring between different key points on graphene C54H18(D6h) representative patch, are given to explore the possible reaction mechanism which is one-step reaction. Finally, according to the electron spin density distribution of radical isomers, the possible products of C54H18-X2are invested. The results are verified by analysis of relative energy and HOMO-LUMO gap. Hydrogenated graphene takes a1,2-addition and fluorinated graphene take1.4-addition.Secondly, we studied the interaction between D3h-C74and lanthanum atom and obtained the interaction potential. Optimized structures show that there are three equivalent stable isomers, with La located about1.7A off-center. There is one transition state between every two stable isomers. According to the minimum energy pathway, the possible movement trajectory A-B-A-B-A-B-A of La in the D3h-C74cage is explored. The calculated energy barrier for La atoms moving from the stable isomer to the transition state is18.4kcal/mol. In addition, we predict the dynamic NMR spectra of La@C74according to the trajectory. There are9lines in the spectrum. By comparing the results of DFT, the stable structure La@C74, potential energy curves and vibration frequency of La, we obtained a more reasonable force field. This laid the foundation for molecular dynamics simulation.In addition, Eu@C82(C2v) has been investigated by relative density function theory method. From thermodynamics and chemical reaction activity, we analyzed the relative energy and HOMO-LUMO gap of the two structures, which Eu located at an off-centered position near the C-C bond and near a hexagonal ring of the C2v-C82cage along the C2axis. It is more stable for Eu@C82with Eu located near a hexagonal ring along the C2axis. Finally, we calculated potential energy surface and obtained the movement area of Eu in C2v-C82.