有机半导体苝的DFT理论计算研究

采用密度泛函理论(DFT)方法对苝进行了B3LYP/6-31G水平上的分子结构优化、IR光谱、Raman光谱、THz光谱、UV-Vis光谱、分子前线轨道、分子电子密度、Mulliken电荷等理论计算。研究结果表明:理论计算结果与实验数据吻合得较好,对IR、THz、UV-Vis吸收光谱和Raman散射光谱中的特征峰进行了归属,发现苝的THz光谱有三个特征吸收峰,它们分别位于2.94、5.46和7.77 THz,其中5.46 THz的吸收是最强的,它是由以C4-C1-C11-C16为轴的苝分子面外对称弯曲振动产生的。苝在UV-Vis光波段有三个吸收峰,峰值波长分别位于420.79、328.14及303.80 nm,其中420.79nm的紫外吸收峰最强。前线轨道计算表明苝分子的HOMO与LUMO能量差值为3.077eV,它与用UV-Vis的理论计算能隙2.946eV仅有0.131eV(4.45%)的偏差。

The Study on Organic Semiconductor Perylene by DFT Theoretical Calculation

The geometry optimization, IR spectrum, Raman spectrum, THz spectrum, UV-Vis spectrum, frontier molecular orbitals, electron density as well as Mulliken charges calculations on perylene are carried out by using Density Functional Theory (DFT) at B3LYP/6-31G level. Research results show that the theoretical calculation results agree well with experimental data, the characteristic peaks in IR, THz, UV-Vis and Raman spectra have been assigned. It is found that perylene has three characteristic absorption peaks in THz spectrum, they are located at 2.94, 5.46 and7.77 THz, respectively, among them, the strongest absorbance peak locates at 5.46 THz which is caused by the out-of-plane symmetric bending vibration on C4-C1-C11-C16 axis of perylene. There are three UV-Vis absorption bands centered at 420.79, 328.14 and 303.80 nm, the strongest peak is 420.79 nm. The frontier molecular orbital calculation on perylene shows that the energy difference between HOMO and LUMO is 3.077 eV, which has a 0.131 eV(4.45%)deviation compared with the Eg calculated from UV-Vis absorption.