Theoretical prediction of vibrational spectra: The out-of-plane force field and vibrational spectra of pyridine

The harmonic force field for the out-of-plane vibrations of pyridine has been calculated from ab initio Hartree-Fock wavefunctions obtained with a 4–21 basis set of contracted Gaussians. To account for systematic errors, the calculated force constants were scaled, using only two independent sclae factors which were transferred unchanged from benzene. The resulting scaled quantum mechanical force field, which is strictly a priori in that it is not based on any experimental data on pyridine, predicts the 64 out-of-plane fundamental frequencies of pyridine and its deuterated isotopomers of C_2v symmetry with a mean deviation from experiment of only 8.5 cm^?1. Addition of polarization functions to the basis set for the nitrogen atom and refinement of the two scale factors by fitting them to the observed pyridine spectra produce no significant improvement in the fit. Assignments of the vibrational spectra are discussed.     

Calculation of force constants and interpretation of vibrational spectra of cyclopentadiene and its deutero derivatives

The force constants, influence coefficients, frequencies, and forms of the vibrations are calculated and an interpretation is given for the vibrational spectra of cyclopentadiene and its deutero derivatives.     

Interplanar force constants and phonon frequency spectra

The concept of interplanar forces is used to calculate bulk phonon frequency spectra. Numerical calculations are performed for-iron.     

The spectra and structure of indium iodide: The rotational and vibrational constants of the B 1 state

The rotational constants of the B 1 state of indium iodide are reported for the first time as B_e = 0.037533 cm⁻¹ and α_e = 0.000289 cm⁻¹ while T_e = 25050.60 cm⁻¹ for the B1-X0⁺ transition. Accurate vibrational constants are also computed from measured Q heads as ω_e= 146.36 cm⁻¹ and ω_eχ_e = 2.20 cm⁻¹.     

The vibrational spectra of dibenzofuran

Infrared spectra, polarized along all three orthogonal crystal axes of dibenzofuran, have been recorded from 50 to 3500 cm^?1. The polarized Raman spectra of single crystals have been measured in all possible crystal orientations, and this information has been supplemented by the measurement of depolarization ratios of the Raman lines in solution and melt spectra. This work extends the range of an earlier study carried out before the crystal structure of dibenzofuran was known. With the new data, several changes in the assignment of the molecular fundamentals are necessary; even so, the experimental assignments remain incomplete in many instances. Some lattice modes of the single crystal were observed in the infrared and Raman spectra, and a partial assignment is presented.     

The spectra and structure of indium iodide: The rotational and vibrational constants of the A0 state

The rotational constants of the A0⁺ state of InI are reported for the first time as B_e = 0.038077 cm⁻¹ and α_e = 0.0002373 cm⁻¹, while T_e = 24402.91 cm⁻¹ for the A0⁺-X0⁺ transition. Accurate vibrational constants for both the A0⁺ and X0⁺ states are computed from the derived band origins.     

The microwave spectra and vibration-rotation interaction constants for CD3I in the excited vibrational states

The microwave spectra in the J = 1 → 3 region for CD₃I has been observed and six excited vibrational states assigned. The vibration rotation interaction constants, α^B and nuclear quadrupole coupling constants, eQq, have been determined for the states: ν₂, ν₃, ν₅, ν₆, 2ν₃, and ν₃ + ν₆. For the degenerate vibrational states, the l type doubling constants, q_t were determined.     

The vibrational spectra of magnesium pyrophosphate polymorphs

The Raman spectra were measured and analyzed for both α- and β-Mg₂P₂O₇. The IR and Raman spectra were interpreted for both phases using factor group analyses. The spectral features predicted with factor groups arising from the X-ray crystallographic space groups $\text{P2}{}_1\text{c}$ ? c⁵_2h and $\text{C2}\text{m}$ ? C³_2h for α-Mg₂P₂O₇ and β-Mg₂P₂O₇, respectively, fit the observed results. Bands observed in the Raman spectrum for β-Mg₂P₂O₇ are consistent with a linear bond angle while those for α-Mg₂P₂O₇ are consistent with a bent P-O-P bond angle. No soft modes were observed in the Raman spectra indicating that the phase transition between the two phases is not a second order process.     

HOF分子非谐性力场、光谱常数和振动能级的迭代三激发耦合簇计算

采用包含迭代三激发的耦合簇理论（ CC3和CCSDT-3）,在aug-cc-pVTZ基组水平上对HOF分子几何构型进行优化。通过解析二阶导数结合有限差分技术获得HOF二阶、完全三阶和半对角四阶力场。通过非谐性分析,得到其基频、旋振相互作用常数、非谐性常数和离心畸变光谱常数。应用二阶振动微扰理论（VPT2）得到HOF多个泛频峰位置。目前计算值与实验及其它文献结果符合良好。     

HOF分子非谐性力场、光谱常数和振动能级的迭代三激发耦合簇计算

采用包含迭代三激发的耦合簇理论(CC3和CCSDT-3), 在aug-cc-pVTZ基组水平上对HOF分子几何构型进行优化. 通过解析二阶导数结合有限差分技术获得HOF二阶、完全三阶和半对角四阶力场. 通过非谐性分析, 得到其基频、旋振相互作用常数、非谐性常数和离心畸变光谱常数. 应用二阶振动微扰理论(VPT2)得到HOF多个泛频峰位置. 目前计算值与实验及其它文献结果符合良好.     

The vibrational spectra of some isotopic species of propionitrile

The infrared and Raman spectra of CH₃CH₂CN, CH₃CD₂CN, and CD₃CH₂CN, and the infrared spectrum of CH₃CH₂¹³CN were investigated in detail between 6000 and 100 cm⁻¹. Some infrared measurements of other isotopic species are also reported and partial assignments given. All fundamentals of propionitrile-d₀, -d₂, -d₃, and -¹³CN were assigned, together with a large number of mainly binary combination bands for which a general method of assignment is given. Several Fermi resonances were detected and the unperturbed positions of some of the levels involved were calculated. Special attention was paid to the CH stretching vibrations for which persisting wrong assignments exist in the literature, and to the methyl torsion frequencies which were determined for the four isotopic species above. A valence force field was calculated, and the potential energy distribution of the normal vibrations is tabulated.