Use of relaxation viscoelastic model in calculating uniaxial homogeneous strains and refining the interpolation equations for maxwellian viscosity

The work applies the relaxation viscoelastic model proposed in [1–3] for calculations of high-rate deformation of bars and plates and for refining the interpolation equations of Maxwellian viscosity χ (a magnitude inverse to the relaxation time τ of the tangential stresses) by means of them. These calculations were carried out to study the dependence of the dynamic yield limit σ_g on the deformation rate ?^·. The authors propose that the dependence σ_g(?, T) in ?^· be transformed, such that χ = ?^· (σ, T) (here σ is the intensity of the tangential stresses and T is temperature) in order to construct interpolation equations for Maxwellian viscosity χ. A numerical analysis demonstrated that this equation leads to the correct qualitative dependence in calculations of σ_g (?^·). A correction factor is introduced into the equation χ = χ(σ, T) in order for the numerical calculations to quantitatively coincide with the experimental data in this work.     

S 1 ←S 0 vibronic spectrum and the structure of the chloral molecule in theS 1 stateS 0 vibronic spectrum and the structure of the chloral molecule in theS 1 state

The vibronic absorption spectrum of chloral (CCl₃COH) vapors is studied in the region of S₁ ← S₀ electron transition (32,000–28,700 cm⁻¹). The 29,070 cm⁻¹ vibronic transition (not observed because of low intensity) is believed to be the ‘start’ of the electron transition. Several fundamentals are found in the S₀ and S₁ states. Inversion splitting of the zero vibrational level in the S₁ state of chloral, indicating a nonplanar structure of the carbonyl fragment, is found. The intensity ratio of the torsional transition bands indicates that the S₁ ← S₀ electronic excitation of the chloral molecule causes significant changes in the orientation of the −CCl₃ group relative to the molecular framework. The potential functions of internal rotation (S₀ and S₁ states) and inversion (S₁ state) of the chloral molecule are determined from experimental data. The potential barriers of internal rotation (S₀ and S₁ states) and inversion (S₁ state) are 380, 780, and 760 cm⁻¹ (4.5, 9.3, and 9.1 kJ/mole), respectively. M. V. Lomonosov Moscow State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 3, pp. 507–513, May–June, 1998.     

One- and Two-Dimensional Torsion-Inversion Models for the Fluoral Molecule (CF3CHO) in Excited Electronic States

The structure of the conformationally nonrigid fluoral molecule (CF₃CHO) in the ground (S₀) and lowest excited triplet (T₁) and singlet (S₁) electronic states was studied by ab initio quantum-chemical methods. The equilibrium geometric parameters and harmonic vibrational frequencies of the molecule in these electronic states were determined. The calculations demonstrated that the electronic excitation causes substantial changes in the molecular structure involving the rotation of the CF₃ top and the deviation of the CCHO carbonyl fragment from planarity. The quantum-mechanical problems for large-amplitude vibrations, namely, for the torsional vibration in the S₀ state and the torsional and inversion vibrations (nonplanar carbonyl fragment) in the T₁ and S₁ states, were solved in the one- and two-dimensional approximations. A comparison of the results of calculations revealed the correlation between the torsional and inversion motions.     

Effect of Ethanedioic Acid Additives on the Dissolution of Manganese Oxides in Sulfuric Acid Solution

The effect of ethanedioic acid additives on the rate of manganese(IV) oxide dissolution in sulfuric acid solutions was studied by kinetic and electrochemical methods. Interaction modes were established, and some details of the studied process mechanism were elucidated. Interaction schemes corresponding to the observed kinetic dependences were proposed.     

Vibronic spectra,ab initio calculations,and structures of conformationally non-rigid molecules of oxalyl halides in the ground and lowest excited electronic states. Part V: Oxalyl chloridefluoride (COCl–COF)

The structure and conformational dynamics of the COCl–COF molecule in the ground and lowest excited electronic states were investigated theoretically by the CASPT2/cc-pVTZ method. The equilibrium geometric parameters, harmonic vibrational frequencies, potential functions of internal rotation, and adiabatic transition energies were obtained. According to the results of calculations, the molecule in the ground electronic state exist as the trans and gauche (dOCCO ~30–40°) conformers with a low potential barrier to gauche–gauche transition therefore it is impossible to exclude existence of the cis conformer (instead of gauche) with a very broad and flat potential minimum. For all the investigated excited electronic states of oxalyl chloridefluoride molecule calculations predicted the trans and cis conformers. The strong coupling of internal rotation around the C–C bond and non-planar vibrations of carbonyl fragments was found for the excited electronic states. The results of calculation were utilized for reanalysis of experimental \( \tilde{A}^{1} A^{\prime \prime} \leftarrow \tilde{X}^{1} A^{\prime} \) and \( \tilde{a}^{3} A^{\prime \prime} \leftarrow \tilde{X}^{1} A^{\prime} \) vibronic spectra reported in Kidd and King (J Mol Spectrosc 50:209–219 (1974), and ibid. 48:592–599 (1973)). The vibrational assignment that does not contradict the vibrational spectroscopy data and results of calculations was obtained.     

Two-loop corrections to the potential of a pointlike charge in a superstrong magnetic field

The potential of the pointlike charge in a superstrong homogeneous magnetic field B ? m _e ² /e ³ ≈ 6 × 10¹⁵ G is considered. It is well known that Coulomb potential is significantly modified by taking into account vacuum polarization (calculated in one loop approximation). We consider electron selfenergy and correction to the vertex function at one loop, and show that these diagrams are not enhanced by magnetic field like eB.We calculate two-loop corrections to the vacuum polarization and find that these contributions are small.     

The simplest galilean‐invariant and thermodynamically consistent conservation laws

This paper gives an introduction to formalization of Galileaninvariant and thermodynamically consistent equations of mathematical physics in which unknowns are transformed in rotations by irreducible representations of integer weights. This formalization is based on the theory of representations of the group SO(3).     

Remembrances of Sergei L'vovich Sobolev

Translated from Sibirskii Matematicheskii Zhurnal, Vol. 30, No. 3, pp. 214–216, May–June, 1989.