Soares Vanny Alberto, da Silva Gonçalves Arlan
Department of Chemistry, Federal University of Espírito Santo, Av. Fernando Ferrari, Vitória, 29075-910, Espírito Santo, Brazil.
Department of Chemistry, Federal Institute of Education, Science and Technology of Espírito Santo, Av. Min. Salgado Filho, Vila Velha, 29106-010, Espírito Santo, Brazil.
J Mol Model. 2025 Jan 30;31(2):70. doi: 10.1007/s00894-025-06285-z.
This study presents quantum chemical analysis of 14 distinct carbon-based nanostructures (CBN), ranging from simple molecules, like benzene, to more complex structures, such as coronene, which serves as an exemplary graphene-like model. The investigation focuses on elucidating the relationships between molecular orbital (MO) energies, the energy band gaps, electron occupation numbers (eON), electronic conduction, and the compound topologies, seeking to find the one that approaches most of a graphene-like structure for in silico studies. Through detailed examination of molecular properties including chemical hardness and chemical potential, we demonstrate that the electronic exchange between orbitals is directly influenced by the structural topology of the carbon-based nanostructures, as the electron occupation numbers and the molecular orbital energies. Raman theoretical analysis was performed, ensuring the approximation to a graphene structure by its experimental fingerprint comparison. The correlations presented here offer an approach for anticipating electronic conductivity in graphene-like materials, as well as the confirmation of coronene as a graphene nanostructure for theoretical analyses.
The models were designed at Ghemical software optimized at Tripos5.2 force field and properly protonated on the peripheral carbons. The models were then optimized by PM7 semiempirical method using MOPAC2016 to minimize the gradient energy before applying the DFT calculations. After that, the model's geometry was finally optimized at ab initio B3LYP hybrid functional and 6-31 G* basis, using ORCA5.0.4. The eON, the MO energies and the Raman spectrum were obtained with the same methods, making possible the spectrum extraction without the interference of H atoms, approaching the analyses to graphene-like topologies.
本研究对14种不同的碳基纳米结构（CBN）进行了量子化学分析，这些结构从简单分子（如苯）到更复杂的结构（如并五苯）不等，后者可作为类石墨烯模型的典范。研究重点在于阐明分子轨道（MO）能量、能带隙、电子占据数（eON）、电子传导与化合物拓扑结构之间的关系，旨在找到在计算机模拟研究中最接近类石墨烯结构的一种。通过对包括化学硬度和化学势在内的分子性质进行详细研究，我们证明了轨道间的电子交换直接受碳基纳米结构的结构拓扑影响，就如同电子占据数和分子轨道能量一样。进行了拉曼理论分析，通过与实验指纹进行比较确保接近石墨烯结构。这里呈现的相关性为预测类石墨烯材料中的电子导电性提供了一种方法，同时也证实了并五苯作为用于理论分析的石墨烯纳米结构。
模型在Ghemical软件中设计，该软件在Tripos5.2力场下进行了优化，并在外围碳原子上进行了适当的质子化。然后使用MOPAC2016通过PM7半经验方法对模型进行优化，以最小化梯度能量，之后再应用密度泛函理论（DFT）计算。在此之后，最终使用ORCA5.0.4在从头算B3LYP混合泛函和6 - 31G*基组下对模型的几何结构进行优化。使用相同的方法获得eON、MO能量和拉曼光谱，使得在没有H原子干扰的情况下提取光谱成为可能，从而使分析更接近类石墨烯拓扑结构。
