Vibrational spectra and structural dynamic models of halosubstituted formaldehyde

The DFT/B3LYP method with 6-31G*(**) basis sets has been used to analyze the vibrational spectra of halo-substituted formaldehyde in the anharmonic approximation. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 683–686, September–October, 2006.     

Anharmonic analysis of vibrational states for five-membered heterocyclic compounds

We have used the DFT/B3LYP method with 6-31G*(**) basis sets for analysis of the vibrational spectra and geometric structure of pyrrole, furan, thiophene, and selenophene in the anharmonic approximation. We have determined the influence of resonance effects on the nature of the vibrational states. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 153–156, March–April, 2007.     

Structural Dynamic Models and Vibrational Spectra of Nitrobenzene and Nitropyridines

Using the DFT/B3LYP method with the basis sets 6-31G*(**), we analyzed the vibrational spectra of nitrobenzene and nitropyridines for free molecules and their solutions in water, ethanol, and benzene. The influence of a solvent on the behavior of the characteristic spectral parameters of nitrobenzene is revealed, and the assignment of vibrations for nitropyridines is given. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 4, pp. 450–453, July–August, 2005.     

Structural dynamic models and anharmonic analysis of vibrational states of polychloro-substituted dibenzo-<Emphasis Type="Italic">p</Emphasis>-dioxin

We have analyzed the vibrational spectra of β-tetrachloro-substituted and ortho-chlorosubstituted dibenzo-p-dioxin using the DFT/B3LYP/6-31G(d) method, in the anharmonic approximation. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 21–24, January–February, 2007.     

Quantum chemical calculation of normal molecular vibrations for substituted five-member chalcogen heterocyclic compounds taking anharmonicity into account

The DFT/B3LYP/6-31G* method is used in an anharmonic approximation to analyze the vibrational spectra of substituted furan, thiophene, and selenophene (3,4- and 2,5-dimethyl-, dichloro-, and diaza-; and 2,3,4,5-tetrachloro-). The influence of resonance effects is clarified. in final form, December 16, 2008. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 2, pp. 170–175, March–April 2009.     

Analysis of vibrational spectra of methyl-substituted uracils in the anharmonic approximation

We have analyzed the vibrational spectra of uracil and its methyl-substituted derivatives using the DFT/B3LYP/6-31G(p,d) method, in the anharmonic approximation. We have shown that it is possible to use second-order anharmonic theory of vibrational spectra in predictive calculations for substituted uracils. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 431–436, July–August, 2006.     

Anharmonic force constants of GaSb from the measured third order elastic constants at 300°K

The third-order elastic constants of single crystal GaSb are determined using ultrasonic pulse interferometer at 10 MHz. The constants at 300°K, in units of 10¹¹ N.m.⁻², are C_l11 = ™ 4 ·75 ± 0·06 C₁₄₄ = + 0·50 ± 0·25 C₁₁₃ = ™ 3 ·08 ± 0·02 C₁₆₆ = ™ 2·16 ± 0·13 C₁₂₃ = ™ 0 ·44 ± 0·29 C₄₅₆ = ™ 0·25 ± 0·15 These constants are used to evaluate the three anharmonic first and second neighbour force constants based on modified Keating’s model. The constants are (in units of 10¹¹ N.m⁻²)γ=− 2·406;δ=0·407;ε=−0·222.     

Octic Anharmonic Oscillators: Perturbed Coherent States and the Classical Limit

We use the Poincaré-Linstedt method to find a classical perturbation solution to the octic anharmonic oscillator. Next, we derive perturbed coherent states for this system, calculate the expectation value of the -operator in them and enforce a limiting process to retrieve the classical result from the corresponding quantum one. We have observed a frequency shift proportional to the sixth power of the amplitude for this system. Our results are in agreement with those obtained from Taylor-series method.     

Vibrational properties of graphene and graphene layers

The phonon dispersions of graphene and graphene layers are theoretically investigated within fifth‐nearest‐neighbor force‐constant approach. Based on their symmetry groups, the number of Raman‐ and infrared‐active modes at the Γ point is given. Interatomic force constants are recalculated by fitting them to experimental phonon energy dispersion curves. Wavenumbers of optically active modes are presented as a function of number of layers (n). Our calculated results reproduce well the experimental data of G peak for graphene (1587 cm⁻¹) and graphite (1581.6 cm⁻¹) and clearly give the relation that ω_G = 1581.6 + 11/(1 + n^1.6). Copyright © 2009 John Wiley & Sons, Ltd.     

Joint Rotational Analysis of 16 Vibrational States of HDSe

High-resolution Fourier transform spectra of HD⁸⁰Se in the region of the ν₁+ν₃, 2ν₂+ν₃, 2ν₁+ν₂, 3ν₁, and ν₂+2ν₃ absorption bands, with centers located between 4000 and 5500 cm⁻¹, were recorded and rovibrationally analyzed. Energies of the (101), (021), (210), (300), and (012) states, together with those of the formerly reported (010), (100), (020), (001), (120), (110), (030), (011), (200), (002), and (003) states, were jointly used as input information in a “global fit” procedure. This fit provided 161 spectroscopic parameters which reproduce 3323 observed energies with accuracies close to experimental uncertainties. These parameters are compared with those predicted from H₂Se. Moreover, experimental band centers for HSeD are compared with those calculated theoretically.     

Vibrational spectra of activated rei of wolframile-phosphate glasses

The vibrational spectra of wolframile-phosphate glasses with a high concentration of WO ₂ ²⁺ and Ln³⁺ ions were investigated and the structure of these glasses was analized. It is shown that the investigated glasses are formed predominantly by chain polyphosphates. Tungstate enters into the net of the glass in octahedral coordination, “stitching” the polyphosphate chains together but not isomorphously substituting phosphorus. In the glass structure nonlinear wolframile groups with the multiple tungsten-oxygen bonds are formed. The introduction of lanthanide oxides into the glass composition causes the average degree of its polymerization to decrease. F. Skorina Gomel' State University, 104 Sovetskaya St., Gomel', 246699, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 2, pp. 236–241, March–April, 1997.     

Vibrational spectra and intramolecular vibrational redistribution in methane and its isotopomers

An improved U(2) algebraic model is introduced to study the stretching and bending vibrational spectra of methane and its isotopomers.The algebraic model with fewer parameters reproduces the experimental spectra with good precision.Moreover,the obtained parameters describe well the correct behavior of isotopic substitution.It is shown that the Fermi resonance leads to a very fast intramolecular vibrational redistribution among stretches and bends.     

Anharmonic force fields of cis- and trans-S1 C2H2

We calculate second-order vibrational perturbation theory (VPT2) anharmonic force fields for the cis and trans conformers of S₁ C₂H₂, and compare the results to experiment. The vibrational assignments of recently observed levels belonging to the cis well are of particular interest. A refined estimate of the cis origin position (44,870?±?10?cm^?1) is proposed, and preliminary low-energy fits to the global J?=?K?=?0 trans level structure are also described. The performance of perturbation theory in this isomerizing system is examined, and both surprising successes and failures are encountered. We examine these and their causes, and offer practical suggestions for avoiding the pitfalls of applying perturbation theory to systems with large amplitude motions.     

双原子分子电子光谱的振动结构分析

从电子振转能级的光谱项出发,分析了双原子分子电子振动谱带序和电子振动谱带列的规律,并归纳出德兰德斯表(Deslandres table)及其主要性质。以C₂分子电子振动光谱的斯簧谱带系作为实例,说明了如何对电子振动光谱的测量值进行标识,并将它们按振动结构规律整理成德兰德斯表,从而获得有关分子光谱不同态的非谐性常数、振动频率等重要参数以及任意谱带的波数公式。     

Calculation of Vibrations of Phenyldichloroarsine and Phenyldichlorophosphine and Analysis of Their Structure Parameters

The vibrational spectra of free molecules and aqueous solutions of phenyldichloroarsine and phenyldichlorophosphine have been analyzed by ab initio methods. Characteristic spectral parameters of these compounds, which can be used for monitoring the environment, have been revealed.     

Vibrational and Conformational Analysis of 5-Methyl-2-Hexyne

Infrared and Raman spectra were obtained for 5- methyl-2-hexyne and wereinterpreted with the aid of normal coordinate calculations. The spectra and molecular mechanics calculations show the compound to exist in two spectroscopically distinguishable stable conformations, with the C₁ conformer being only a little more stable than the C_s, conformer. Vibrational assignments were made for both conformers.     

Vibrational Spectra and Normal Coordinate Analysis for an Imidazole Bridged Copper,Zinc Binuclear Complex

Abstract

The normal coordinate analysis of a model compound for Cu, Zn-SOD: [(dtma)CuImZn(dtma)]CIO₄ · 2.5H₂O (where dtma = 4-diethylenetriamineacctate; Im = imidazolate) has been carried out by using a Urey-Bradley force field. According to the molecular structure, 240 internal coordinates were established and 174 theoretical vibrational frequencies were calculated. Due to introducing an appropriate set of internal coordinates and force constants in the course of calculation, the calculated frequencies agree well with the observed values, with the average difference 4.40cm^?1 and the maximum deviation 24.2cm^?1 between them, although the structure of the title compound is complicated. Some structural and spectral properties are here discussed.     

Vibrational Spectroscopic Analysis of L,D-Dipeptides

Raman and infrared spectra of Boc-D-Leu-L-Leu-OMe, Boc-L-Ile-D-aIle-OMe and its N-deuterated derivative have been obtained. Normal mode frequencies on the models of these dipeptides have been calculated and the conformationally sensitive amide I, II, III and V modes are compared with the experimentally observed frequencies. The calculated frequencies are in good agreement with the observed frequencies. It is observed that the amide frequencies in these dipeptides are not very sensitive to their backbone conformation. This is in contrast to the well established conformational dependence of the amide modes in peptides, polypeptides and proteins. The normal mode calculations on these peptides also show absence of mixing in amide I and II modes, and hence lack of appreciable splitting in these modes due to transition dipole coupling.

     

The Vibrational Spectra of a Series of Simple Phosphorus/Chromium Polyoxoanions

The infrared and Raman spectra of polycrystalline samples of K₂HPCr₂O₁₀, Na₃PCr₃O₁₃.3H₂0, K₃PCr₄O₁₆ and (NH₄)₃PCr₄O₁₆ were recorded and discussed. A general vibrational assignment for the internal vibrations of these species is proposed.

The structural characteristics of an interesting series of simple polyoxoanions of the PCr_nO^3- _3n+4 type have been determined recently^1–7. These species are essentially built from a central PO₄ -tetrahedron which share a different number of corners with CrO₄ -tetrahedra.

As part of our present studies on different physico-chemical properties of polyoxoanions, we have investigated the vibrational spectra of crystalline species containing the following anions: HPCr₂O^2- ₁₀, PCr₃O^3- ₁₃ and PCr₄O^3- ₁₆.

As the three species have some common structural features, their vibrational spectra can be analyzed and compared in terms of these common building elements, i. e., terminal CrO₃ and PO groups and POCr bridges.

The interatomic distances in the above mentioned units are also very similar in all the anions and the Cr-O distances are similar to those found in the normal (triclinic) form of K₂Cr₂O₇ ⁸.