C80H80几何结构和电子性质的密度泛函研究

采用密度泛函理论方法中的广义梯度近似,对C₈₀H₈₀几何结构和电子性质进行了研究. 几何结构研究表明:在C₈₀H₈₀可能稳定存在的两种同分异构体中, 连接12个五边形的20个C原子内部氢化,其余60个C原子外部氢化所形成的结构即 H₂₀@C₈₀H₆₀最稳定,其仍然保持I_h对称性. 通过对H₂₀@C₈₀H₆₀的能级、前线轨道和态密度分析可知: 在H₂₀@C₈₀H₆₀中, H原子的原子轨道与C原子的原子轨道之间在占据态轨道上有较强的杂化, H原子对H₂₀@C₈₀H₆₀的占据态轨道的贡献比较大. 其最高占据轨道主要由外部H原子和碳笼来贡献,而最低未占据轨道主要由内部H原子贡献, 表明内外H原子在H₂₀@C₈₀H₆₀的化学反应中承担不同的角色. H₂₀@C₈₀H₆₀为闭壳层结构,所有电子都是配对的,表现为非磁性.

Density functional study on the geometric and electronic properties of C80H80

The generalized gradient approximation based on the density functional theory is used to analyze the geometric and the electronic properties of C₈₀H₈₀. The geometric structure research indicates that between the two possible stable isomers, the isomer with 20 hydrogens connecting 12 pentagons and the 60 others outside is more stable structure. The analyses of the energy level, the orbital wavefunction, and the density of states of H₂₀@C₈₀H₆₀, show that the atomic orbits of the H and C atoms have strong hybridization on the occupied molecular orbits. The low unoccupied molecular orbital of H₂₀@C₈₀H₆₀ is occupied mainly by the H atoms inside the carbon cage, while the high occupied molecular orbital of H₂₀@C₈₀H₆₀ are occupied partly by the H atoms outside the cage. Therefore, the H atoms inside and outside the cage will play different roles in the chemical reaction involving H₂₀@C₈₀H₆₀. The H₂₀@C₈₀H₆₀ shows the character of the closed-shell structures with no magnetic moment.