理论研究铍团簇结构及性质的碳掺杂效应
发布时间：2018-11-14 07:45
【摘要】：在B3PW91/6-311+G(d)水平下优化得到了Ben C(n=1 12)团簇和纯铍团簇的最低能量结构,并对它们的结构特点进行对比。结果表明掺杂的碳原子优先位于铍团簇的表面且趋向于形成四配位的化合物,其中例外的是Be6C中碳原子与三个铍原子成键,这可以归因于Be6团簇非常稳定的八面体结构,如果碳原子与四个铍原子成键就会使稳定的八面体结构遭到破坏;除Be C的最低能量结构为三重态以外,其它所有n=2 12的团簇最稳定结构都为单重态;另外,除n=4、5和6以外其它所有Ben C团簇的最低能量结构与对应的Ben+1团簇的最低能结构构型相似。在Ben C团簇的最低能量结构基础上,使用QCISD(T)方法计算了它们的电子和能量性质:结合能(Eb)、二阶能量分差(Δ2E)、解离能(ΔE)、HOMO-LUMO能隙值等。其中Ben C团簇系列中每一个分子的结合能都比对应的Ben+1团簇的大,这说明碳原子的引入增加了纯铍团簇内部的相互作用。此外,Be3C和Be8C在结合能(Eb)、二阶能量分差(Δ2E)、垂直电离能(VIPs)等性质演变中表现出特殊的稳定性从而被看作是幻数结构。对两团簇的分子轨道分析可以看出两团簇都是全充满的电子壳层结构,Be3C的电子壳层结构为1S21P62S2,Be8C的电子壳层结构为1S21P61D42S21D6,都符合jellium模型,这进一步证明它们特殊的稳定性。而相对于纯铍团簇而言,碳原子轨道的贡献导致分子轨道能级发生了改变,Be8C中碳掺杂使2S轨道能级低于其中的三个D轨道,Be3C中碳掺杂使2S轨道能级低于1D的轨道能级。
[Abstract]:At the B3PW91/6-311 G (d) level, the lowest energy structures of Ben C (nni1 / 12) cluster and pure beryllium cluster are obtained, and their structural characteristics are compared. The results show that the doped carbon atoms are preferentially located on the surface of beryllium clusters and tend to form four-coordinated compounds, except that the carbon atoms in Be6C bond with three beryllium atoms, which can be attributed to the very stable octahedron structure of the Be6 cluster. If carbon atoms bond with four beryllium atoms, the stable octahedron structure will be destroyed. Except that the lowest energy structure of Be C is triplet, the most stable structure of all the other clusters is singlet. In addition, the lowest energy structure of all the Ben C clusters except ndl4 and 6 is similar to that of the corresponding Ben 1 clusters. On the basis of the lowest energy structure of Ben C clusters, the electron and energy properties of Ben C clusters are calculated by QCISD (T) method: second order energy difference of binding energy (螖 2e), dissociation energy (螖 E), HOMO-LUMO energy gap), etc. The binding energy of each molecule in the Ben C cluster is higher than that of the corresponding Ben 1 cluster, which indicates that the introduction of carbon atoms increases the interaction within the pure beryllium cluster. In addition, Be3C and Be8C show special stability in the evolution of the second order energy difference (螖 2e) and vertical ionization energy (VIPs) of binding energy (Eb), so they are regarded as magic number structures. The molecular orbital analysis of the two clusters shows that both clusters are full of electronic shell structure, and the electronic shell structure of Be3C is 1S21P62S2S2Be8C, which accords with the jellium model, which further proves their special stability. Compared with pure beryllium clusters, the contribution of carbon atom orbital leads to the change of molecular orbital energy level. Carbon doping in Be8C makes the energy level of 2S orbit lower than that of three D orbitals, and carbon doping in Be3C makes the energy level of 2S orbital lower than that of 1D.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O641.1
本文编号：2330516
[Abstract]:At the B3PW91/6-311 G (d) level, the lowest energy structures of Ben C (nni1 / 12) cluster and pure beryllium cluster are obtained, and their structural characteristics are compared. The results show that the doped carbon atoms are preferentially located on the surface of beryllium clusters and tend to form four-coordinated compounds, except that the carbon atoms in Be6C bond with three beryllium atoms, which can be attributed to the very stable octahedron structure of the Be6 cluster. If carbon atoms bond with four beryllium atoms, the stable octahedron structure will be destroyed. Except that the lowest energy structure of Be C is triplet, the most stable structure of all the other clusters is singlet. In addition, the lowest energy structure of all the Ben C clusters except ndl4 and 6 is similar to that of the corresponding Ben 1 clusters. On the basis of the lowest energy structure of Ben C clusters, the electron and energy properties of Ben C clusters are calculated by QCISD (T) method: second order energy difference of binding energy (螖 2e), dissociation energy (螖 E), HOMO-LUMO energy gap), etc. The binding energy of each molecule in the Ben C cluster is higher than that of the corresponding Ben 1 cluster, which indicates that the introduction of carbon atoms increases the interaction within the pure beryllium cluster. In addition, Be3C and Be8C show special stability in the evolution of the second order energy difference (螖 2e) and vertical ionization energy (VIPs) of binding energy (Eb), so they are regarded as magic number structures. The molecular orbital analysis of the two clusters shows that both clusters are full of electronic shell structure, and the electronic shell structure of Be3C is 1S21P62S2S2Be8C, which accords with the jellium model, which further proves their special stability. Compared with pure beryllium clusters, the contribution of carbon atom orbital leads to the change of molecular orbital energy level. Carbon doping in Be8C makes the energy level of 2S orbit lower than that of three D orbitals, and carbon doping in Be3C makes the energy level of 2S orbital lower than that of 1D.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O641.1
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