Department of Physics, P.C. Jabin Science (Autonomous) College, Hubli 580031, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2010 Dec;77(5):918-26. doi: 10.1016/j.saa.2010.06.033. Epub 2010 Jun 25.
FT-IR (4000-400 cm(-1)) and FT-Raman (3500-50 cm(-1)) spectral measurements of solid sample of 2-chloro-5-bromopyridine have been done. Ab initio and DFT calculations have been performed giving energies, optimized structures, harmonic vibrational frequencies, depolarization ratios, IR intensities, Raman activities and atomic displacements. Furthermore, force field calculations have been performed by normal coordinate analysis. A complete assignment of the observed spectra, based on spectral correlations, electronic structure calculations and normal coordinate analysis, has been proposed. The results of the calculations have been used to simulate IR and Raman spectra for the molecule that showed good agreement with the observed spectra. The SQM method, which implies multiple scaling of the DFT force fields, has been shown superior to the uniform scaling approach. The energy and oscillator strength calculated by Time-dependent DFT results are in good agreement with the experimental results.
对 2-氯-5-溴吡啶的固态样品进行了傅里叶变换红外（4000-400 cm(-1)) 和傅里叶变换拉曼（3500-50 cm(-1)) 光谱测量。进行了从头算和密度泛函理论计算，给出了能量、优化结构、简正振动频率、去偏振比、红外强度、拉曼活性和原子位移。此外，还通过正则坐标分析进行了力场计算。根据光谱相关性、电子结构计算和正则坐标分析，提出了对观察到的光谱的完整分配。计算结果用于模拟分子的红外和拉曼光谱，与观察到的光谱吻合较好。表明 SQM 方法（即对 DFT 力场进行多次缩放）优于均匀缩放方法。通过时间相关密度泛函理论计算得到的能量和振子强度与实验结果吻合较好。
