Department of Physics, Bishop Moore College, Mavelikara, Alappuzha 690110, Kerala, India; Department of Physics, CMS College, Kottayam 686001, Kerala, India.
Department of Physics, Bishop Moore College, Mavelikara, Alappuzha 690110, Kerala, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2014 Mar 25;122:375-86. doi: 10.1016/j.saa.2013.11.077. Epub 2013 Nov 20.
The conformational behavior and structural stability of trans-1,2-bis(3,5-dimethoxy phenyl)-ethene (TDBE) were investigated by using density functional theory (DFT) method with the B3LYP/6-311++G(d,p) basis set combination. The vibrational wavenumbers of TDBE were computed at DFT level and complete vibrational assignments were made on the basis of normal coordinate analysis calculations (NCA). The DFT force field transformed to natural internal coordinates was corrected by a well-established set of scale factors that were found to be transferable to the title compound. The infrared and Raman spectra were also predicted from the calculated intensities. The observed Fourier transform infrared (FTIR) and Fourier transform (FT) Raman vibrational wavenumbers were analyzed and compared with the theoretically predicted vibrational spectra. Comparison of the simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecules has been obtained by mapping electron density isosurface with electrostatic potential surfaces (ESP).
采用密度泛函理论（DFT）方法，在 B3LYP/6-311++G（d，p）基组组合下，研究了反式-1,2-双（3,5-二甲氧基苯基）乙烯（TDBE）的构象行为和结构稳定性。在 DFT 水平上计算了 TDBE 的振动波数，并基于正则坐标分析计算（NCA）进行了完整的振动分配。通过一组经过良好验证的比例因子对转换到自然内坐标的 DFT 力场进行了修正，这些比例因子被发现可转移到标题化合物。还从计算的强度预测了红外和拉曼光谱。分析了观察到的傅里叶变换红外（FTIR）和傅里叶变换（FT）拉曼振动波数，并将其与理论预测的振动光谱进行了比较。模拟光谱与实验光谱的比较提供了关于计算方法描述振动模式能力的重要信息。通过绘制等电子密度与静电势表面（ESP）的关系图，可以获得分子的大小、形状、电荷密度分布和化学反应活性点的信息。
