摘要为了有效准确的研究(BN)25纳米管的结构和性能，对各种(BN)25纳米管构型进行结构优化和频率计算，找到了基态构型。并对基态构型的多种物理、化学性能进行计算研究。内容如下：

   1。对(BN)25纳米管的构型进行优化，得到其基态结构。确定其多重度为1，对称性为C1。它是由16个六元环，10个五元环构成，其中11和44、10和45、47和49号原子的连键发生断裂现象。

   2。结构稳定性：对(BN)25纳米管的结构稳定性进行分析，发现，其平均结合能为0。251ev，能隙为3。914ev；表明(BN)25纳米管具有较高的化学稳定性。86312

   3。自然键轨道：由于原子受到不同势场的作用，B原子和N原子之间存在电荷转移，原子内部发生了杂化。除此之外，不同原子间也有杂化现象。

   4。极化率：(BN)25纳米管极化率张量主要分别在XX、YY、ZZ方向。XX方向上的极化率张量分量最大为457。799；YY和ZZ方向上的极化率张量差不多。而在XY和YZ方向上的张量分布很少，几乎为零。

   5。振动光谱：在红外光谱中，最强的振动峰位于波数为1470。85cm-1处，该振动模式对应的是笼环的伸缩运动。拉曼光谱中，最高的峰位于波数886。30cm-1处，对应为伸缩运动的振动模式，稍比其低一点的峰位于波数786。06cm-1处。其它频率对应的振动明显弱了许多，表明在这些频率下，其振动的拉曼活性低。

   6。芳香性：(BN)25纳米管在试探原子Bq位于在空间几何构型的的中心(0。000nm)和到平面的垂直距离为0。025nm、0。050nm、0。075nm、0。100nm时均具有芳香性；随着试探原子与参考平面的垂直距离增大，NICS的绝对值也不断增加，表明其芳香性不断增加。

毕业论文关键词： (BN)25纳米管；结构与性能；密度泛函理论

Abstract To the structure and performance of the accurate and effective research (BN) 25 nanotubes, using density functional theory (DFT) B3LYP and 6-31G (d) basis sets on various (BN) 25 nanotubes configuration of structural optimization and frequency calculation and find the ground state configuration。 The structure stability of the ground state configuration of (BN)25 nanotubes, natural building track (NBO), polarization ratio, vibration spectrum analysis and NICS were calculated and analyzed。The main contents are:

1。The state structures: by (BN)25 nanotubes various configurations optimized to give its ground state structure。 As can be seen, the tubular (BN)25 is a multiple of 1, symmetry C1。 It is composed of 16 six-membered rings, 10 five-membered ring structure, 11 and 44,10 and 45, 47 and 49 atoms bond breakage occurs。

2。Structural Stability: Structural stability of (BN)25 nanotubes were analyzed and found that the average binding energy 0。251ev, the energy gap was 3。914ev; show (BN) 25 nanotubes have a high chemical stability。

3。NBO: 2s orbital B atoms and N atoms lose electrons, 2p orbital the electron, atom took place within hybrid。 In addition, there are also hybrid between atoms, these hybrid orbitals interact to form chemical bonds between atoms determines the stability of the clusters and special physical and chemical properties。

4。Polarization: (BN)25 nanotubes susceptibility tensor mainly in XX, YY, ZZ direction respectively。 Polarizability tensor XX direction component of a maximum of 457。799; susceptibility tensor YY and ZZ direction almost。 The tensor in the XY and YZ direction distribution rarely, almost zero。

5。Vibrational spectra: in the infrared spectrum, the strongest peak at the wave number of the vibration 1470。85cm-1 at the vibration mode corresponds to the telescopic movement of fullerenes。 In the Raman spectrum, the most active peak at wave number 886。30cm-1 at the vibration mode of stretching exercise, a little less than the lower peak at wave number 786。06cm-1 place。 Other significant vibration frequency corresponds to a lot of weak, suggesting that at these frequencies, Raman-active vibration low。