Open Hecke chains and free fermions

We consider integrable open-chain models formulated in terms of generators of Hecke algebra. The algebraic analogs of Sklyanin’s commutative transfer matrices are considered for these models. The spectrum of Hamiltonians for open Hecke chains of finite size is deduced for special representations of the Hecke algebra.     

Hydrogen bonded С–H···Y (Y = O,S, Hal) molecular complexes: A natural bond orbital analysis

Hydrogen bonded C–H···Y complexes formed by H₂O, H₂S molecules, hydrogen halides, and halogen-ions with methane, halogen substituted methane as well as with the C₂H₂ and NCH molecules were studied at the MP2/aug-cc-pVDZ level. The structure of NBOs corresponding to lone pair of acceptor Y, n_Y, and vacant anti-σ-bond C–H of proton donor was analyzed and estimates of second order perturbation energy Е⁽²⁾ characterizing donor–acceptor n_Y → σ_C-H^* charge-transfer interaction were obtained. Computational results for complexes of methane and its halogen substituted derivatives show that for each set of analogous structures, the Е_nY→σ*C-H⁽²⁾ energy tends to grow with an increase in the s-component percentage in the lone pair NBO of acceptor Y. Calculations for different C···Y distances show that the equilibrium geometries of complexes lie in the region where the E⁽²⁾ energy is highest and it changes symbatically with the length of the covalent С–H bond when the R(C···Y) distance is varied. The performed analysis allows us to divide the hydrogen bonded complexes into two groups, depending on the pattern of overlapping for NBOs of the hydrogen bridge.     

Evolution of extinction spectra of plasmon resonance nanocolloids in the process of their crystallization

Changes in extinction spectra of nanostructured colloids of plasmon resonance particles are studied at different stages of their crystallization. The spontaneous crystallization is calculated by the method of Brownian dynamics, and the extinction spectra are calculated by the method of coupled dipoles. Based on the example of silver sols, we analyzed how separate parameters of the crystallizing disperse system affect the shape of the extinction contour in the plasmon absorption band.     

Deformation phase transition in vanadium under high pressure

Within the framework of the Landau theory of phase transitions and the density functional method, it is shown that the structural transformation from a body-centered cubic phase to a rhombohedral phase revealed in vanadium at 69 GPa is a first-order deformation phase transition close to a second-order phase transition.     

Numerical simulation of laser welding of thin metallic plates taking into account convection in the welding pool

A new quasi-three-dimensional model of the laser welding of thin metal plates and a numerical algorithm of its implementation are proposed. Computations of thermophysical processes at a laser joining of titanium plates are carried out. It is shown that the new model adequately describes thermophysical and hydrodynamic processes occurring in the welding region.     

Millimeter-wave electron-beam-switched resonance phase shifter

A powerful millimeter-wave phase shifter switched by an electron beam is studied. The operation of the device is based on the phase change in a wave reflected from a microwave resonator, depending on whether this resonator is or is not turned to resonance. Numerical simulation of several designs of the phase shifter is carried out, and the feasibility of its low-power operation is experimentally demonstrated. In the experiments, the typical time of phase change in the electromagnetic wave is 30 ns. It is shown that not only the electron beam, but also the near-electrode plasma, significantly influences the amount and time of phase change in the reflected wave.     

The alpha and omega of the scientific work of Academician Moisei Aleksandrovich Markov

A brief survey of the scientific, scientific-administrative, and public activity of M. A. Markov is given in regard with his centenary (May 13, 1908–October 1, 1994). The outstanding contribution of Moisei Aleksandrovich to the theory of elementary particle physics, gravitation, and cosmology is pointed out.