中文摘要：

应用量子化学方法，通过核独立化学位移（NIcS）和异构体稳定化能（ISE）的计算，研究了苯及第五主族元素取代杂苯分子C5H5X（X=N，P，As，Sb，Bi）的芳香性与稳定性．局域轨道定位函数局部最大值的计算结果表明，分子中C-X成键强度与实验稳定性顺序一致．从头算与密度泛函理论对分子的化学位移计算结果各异，计算值与实验值相关分析表明，Hartree—Fock方法对所研究体系的NICS比密度泛函理论具有更好的相关性．在分子环平面上方0．8～0．9A处的NICS是芳香性判据的最佳选择，由自然定域分子轨道分解NICS最大处的ZZ张量值，结果显示π键对分子的芳香性起主要贡献．异构体稳定化能与NICS（max）的zz张量及π键（NICS（max）zzx）均有很好的相关性，可以表征杂苯分子C5H5X全局芳香性，其顺序为：苯〉吡啶〉磷杂苯〉砷杂苯〉锑杂苯〉铋杂苯．特别地，对这类分子π轨道的研究发现不包含X原子的π轨道将产生异常大的π键芳香性．这一现象可为分子磁性设计提供理论指导．

英文摘要：

In different research fields nucleus independent chemical shift （NICS） has been used frequently as a convenient tool for obtaining information about induced dia-paratropic and paratropic ring currents, especially for the purpose of assign- ing aromaticity and anti-aromaticity to molecules, obviously, aromaticities and magnetic properties of molecules can be measured by NICS. This paper presents the investigation on some important features of benzene and heterobenzenes C5H5X （X=CH, N, P, As, Sb, Bi） based on the analyzing maximum value of NICS above the cycle planar about 0.8-0.9 A. Compared with density functional theory （DFT）, the calculated results by ab initio （HF） are more accurate and acceptable for the NICS of heterobenzenes. There are two primary reasons to explain the phenomenon. First, the correlation coefficient of the proton chemical shifts of XH NMR between calculated and experimental data by HF method is larger than adopted DFT methods. Second, because the ghost position plays a critical role in judging aromaticity, only involving HF method satisfy the results through comparing NICS（1） with the aromaticity of benzene, pyridine and other heterobenzenes in normal tempera- ture and pressure. Furthermore, according to the calculation of natural localized molecular orbitals （NLMO）, we can get a conclusion that the n bonds are main contributions to the zz tensor of NICS（max）, and the order is benzene〉pyridine〉 phosphabenzene〉arsabenzene〉stibabenzene〉bimabenzene. 6 bonds all show 6 aromaticity. However, other bonds＇ anti-aromaticity is revealed. In order to be further studied for aromaticity and chemical shifts of 1H NMR about the hetero- benzenes, the magnitudes induced are depicted by the outer magnetic field. For pyridine, the magnitudes of red area coincide with the proton chemical shifts （α-H〉）,-H〉β-H）; others are in accord with the order （α-H〉β-H〉）,-H）. Finally, the induced magnitudes by the outer magnetic field show the same global aroma