Ab-initio electronic structure studies of mobility paths in fast-ion conductors—I: Results for MI4−3 clusters

We report results of minimum-basis Pseudopotential Hartree-Fock studies of MI₄^?3 clusters (M = Na⁺, K⁺, Ag⁺, and Cu⁺), and of HgI₄^?2. The calculations are designed to characterize local-site effects on mobility paths in solid state electrolytes. We observe qualitatively correct behavior, with Ag⁺ predicted to be the most mobile ion. Quadrupolar polarizability of the metal ion, which is produced by s-d mixing, lowers the energy of trigonal transition state, thus accounting for the observation that quadrupole polarizable species are ideal mobile ions in close-packed halide frameworks. Mulliken populations show that there is considerable local covalency, so that electrostatic potential studies must be done very carefully. Expansion of the I₄ tetrahedron lowers the barrier energy.     

Effect of relaxation phenomena on the strength of plastics exposed to harmonic loads and impacts

It is shown that if the frequency of cyclic loading is varied, the total heat-up is small, and relaxation processes do not play a role (proceed too fast or too slowly), the loading times are additive. It is shown that deviations from this additivity rule manifest themselves in a disproportionally slow increase or even in a decrease of the strength with rising frequency; these deviations may be caused by relaxation factors, i.e., by structural changes and local warming up. It is established that the degree of deviation depends on various factors determining the rate of relaxation, i.e., on the temperature, plastification, and orientation, which is in accordance with ideas on the role of relaxation phenomena in fatigue rupturing but conflicts with the view that the number of load cycles should be the decisive factor. The phenomenon of fatigue rupturing of plastics exposed to repeated impacts is discussed; specific features of impacts are the high loading rate and the rest between the impacts. It is shown that, in spite of the much shorter action time of the load, the strength under repeated impacts is lower than that under harmonic loading, owing to the stronger effect of local excess stresses and disorientation during unloading.Scientific-Research Institute of Plastics, Moscow. Translated from Mekhanika Polimerov, No. 1, pp. 165–168, January–February, 1972.     

The semiclassical self-consistent-field (SC-SCF) approach to energy levels of coupled vibrational modes. II. The semiclassical state-interaction procedure

A method for obtaining energy levels of coupled vibrational modes is described, that utilizes a state-interaction approach combined with semiclassical approximations. The method starts with a semiclassical self-consistent-field calculation of the coupled problem, and uses the eigenstates of the resulting Hartree-like separable SCF vibrational hamiltonian to define a basis set of Hartree products in which the full vibrational hamiltonian is represented and diagonalized. Matrix elements of any interaction potential between single-mode states are approximated semiclassically as the Fourier component of the interaction at the frequency corresponding to the SCF eigenvalue difference. A Fourier-component expression can also be given for the overlap between non-orthogonal single mode states. Thus no wavefunctions ever need to be defined. Application to a sample two-mode problem shows that the method is highly accurate. Further possible applications, in particular to intramolecular rate calculations are noted.     

Investigation of the relief of the fracture surfaces of epoxy compositions subjected to cyclic loading

Epoxy compositions containing various amounts of plasticizer have been fractured by cyclic loading under conditions of circular cantilever bending. The relief of the fracture surfaces is discussed.Design-Technological Scientific Research Institute, Tallinn. Translated from Mekhanika Polimerov, No. 6, pp. 1014–1017, November–December, 1969.     

Effect of aggressive media on the fatigue life of plastics

The dependence of fatigue life on concentration has been obtained for PVC and polystyrene exposed to the action of acetone solutions. As the mechanical stress increases, the role of the aggressivity of the medium diminishes, and its corrosion activitya tends to a minimum (a=1). When a polymer is exposed to the action of a binary liquid, both of whose components are aggressive, a transition region is observed on the log 1/-log C curve. In this region the fracture rate increases sharply.Mekhanika Polimerov, Vol. 4, No. 3, pp. 489–493, 1968     

Acceleration of polarized protons to multi-GeV energies and experiments with polarized protons from 2–6 GeV/c

Acceleration of polarized protons. Experiments with polarized protons. Proton-proton total cross-section. Two and three spin proton elastic scattering measurements. Polarization measurements in nucleon-nucleon elastic scattering. Inelastic interactions. Inclusive lambda production. Coherent polarized proton⁴He interactions. Parity tests.Presented at the Symposium on Hadron-Hadron Scattering at High Energies, Liblice, Czechoslovakia, June 16–21, 1975. Work supported by the U.S. Energy Research and Development Administration.I would like to thank the authors of all the experiments I have mentioned for their information, both published and unpublished.