Department of Physics, A.V.C. College, Mayiladuthurai, Tamilnadu, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2012 Oct;96:207-20. doi: 10.1016/j.saa.2012.03.090. Epub 2012 May 14.
In the present analysis, FT-IR/FT-Raman spectra of the cyclohexanone oxime (CHO, C(6)H(11)NO) are recorded. The observed vibrational frequencies are assigned and the computational calculations are carried out by HF and DFT (B3LYP and B3PW91) methods with 6-311++G(d,p) basis set and the corresponding results are tabulated. In order to yield good coherence with observed values, the calculated frequencies are scaled by appropriate scale factors. The complete assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The alternation of structure of cyclohexanone due to the substitution of NOH is investigated. The vibrational sequence pattern of the molecule related to the substitutions is analyzed. Comparison of the observed fundamental vibrational frequencies of CHO and calculated results by density functional (B3LYP and B3PW91) and HF methods indicates that B3LYP is superior to the scaled HF and B3PW91 approach for molecular vibrational problems. Moreover, (13)C NMR and (1)H NMR chemical shifts are calculated by using the gauge independent atomic orbital (GIAO) method with HF/B3LYP/B3PW91 methods and the same basis set. A study on the electronic properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, are performed by HF and DFT methods. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) was performed. NLO properties and Mulliken charges of the CHO was also calculated and interpreted. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the title compound at different temperatures are calculated in gas phase.
在本分析中，记录了环己酮肟（CHO，C（6）H（11）NO）的傅里叶变换红外/傅里叶变换拉曼光谱。观察到的振动频率被分配，并通过 HF 和 DFT（B3LYP 和 B3PW91）方法进行了计算，使用了 6-311++G（d，p）基组，并列出了相应的结果。为了与观察值产生良好的一致性，通过适当的比例因子对计算频率进行了缩放。根据振动模式的总能量分布（TED），通过量子力学（SQM）方法进行了完整的分配。由于 NOH 的取代，环己酮的结构发生了变化。分析了与取代相关的分子振动序列模式。CHO 的观察到的基本振动频率与密度泛函（B3LYP 和 B3PW91）和 HF 方法的计算结果的比较表明，B3LYP 优于比例 HF 和 B3PW91 方法，适用于分子振动问题。此外，使用 HF/B3LYP/B3PW91 方法和相同的基组通过无规坐标原子轨道（GIAO）方法计算了（13）C NMR 和（1）H NMR 化学位移。通过 HF 和 DFT 方法研究了电子性质；吸收波长、激发能、偶极矩和前沿分子轨道能量。计算的 HOMO 和 LUMO 能量表明电荷转移发生在分子内。除了前沿分子轨道（FMO）之外，还进行了分子静电势（MEP）。还计算并解释了 CHO 的 NLO 性质和 Mulliken 电荷。在不同温度下计算了气相中环己酮肟的热力学性质（热容、熵和焓）。
