Stoner-Wohlfarth-type behavior of a close-packed array of high-anisotropy hexaferrite nanoparticles

Magnetization and remagnetization processes in a close-packed nanodispersed barium hexaferrite powder sample in the magnetically stable state were analyzed. Reversibility effects were discussed in terms of interparticle interaction. Judging from the magnetization curve and the parameters characterizing remagnetization irreversibility, the sample under study is a model system of small Stoner-Wohlfarth particles.     

Quantum-Chemical Study of Structural and Energy Characteristics of Benzonitrile Dimers

Ab initio MP2 calculations with several basis sets proved the existence of a stable benzonitrile dimer with a planar structure and a short contact between the H atom of one molecule and the N atom of another. The structure is greatly stabilized by attraction between the neighboring oppositely directed dipoles and donor-acceptor interaction between the orbital of the lone electron pair of the N′ atom and the vacant antibonding orbital localized on the C-H bond.Original Russian Text Copyright © 2004 by O. V. Sizova, E. P. Sokolova, V. I. Baranovskii, D. A. Rozmanov, and O. A. Tomashenko__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 807–815, September–October, 2004.     

Effect of Ultrasonic Treatment on Pearlite Structure and Properties

The influence of ultrasonic shock treatment on variation in the pearlite structure and properties is studied in the surface layer of carburized steel. It is shown that plastic deformation results in carbon redistribution and formation of new phases.     

Interaction of CdSe/ZnS core-shell semiconductor nanocrystals in solid thin films

The optical properties of CdSe/ZnS semiconductor nanocrystals with the core-shell structure are studied upon visible-laser excitation in a wide range of flux densities. It is demonstrated that the dimensional quantization effect is preserved in the films with a limiting high concentration of nanocrystals. A strong bathochromic shift of the absorption and luminescence peaks relative to the peak positions in the corresponding spectra of nanocrystals in films with a relatively low concentration of nanocrystals and solutions is caused by a high concentration of nanocrystals and the dipole moment related to the asymmetry of the nanoparticles. The shift is varied from 35 to 50 nm depending on the film thickness. The luminescence spectra of the films remain unchanged upon an increase in the laser intensity to 1 × 10⁶ W/cm². The laser action on the nanoparticle films is studied at intensities (5 × 10⁶?1 × 10⁹ W/cm²) higher than the damage threshold.     

Use of the CNDO method for the study of the electronic structure and properties of complexes of the transition metals

Conclusions In our view, the material examined in the present review indicates that, in spite of the appearance of more accurate methods of calculating the electronic structure and the increasing possibilities provided for their realization for fairly complex systems, the applied value of simple semiempirical methods, in particular the CNDO method, is far from exhausted. In the near future, semiempirical calculations will probably provide the chief means of studying the electronic structures of complex molecules, by becoming accessible to an increasing circle of chemists.Leningrad State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 17, No. 3, pp. 549–577, May–June, 1976.     

Indo calculation of electronic spectra for transition metal complexes in the extended approximation of singly excited configurations

Semiempirical INDO-E/S calculations of [RuX₆]^q (X=NH₃, q=+2, +3; X=CN⁻, q=−4, −3) complexes are performed to demonstrate that the MO relaxation in the electronically excited state can be taken into account by introducing certain double excitations into the configuration interaction matrix; the principles of selection of the excitations are discussed. The calculation results are compared with the experimental electronic absorption spectra. St. Petersburg State University. Translated fromZhurnal Struktumoi Khimii, Vol. 37, No. 2, pp. 195–205, March–April, 1996. Translated by I. Izvekova     

Quantum-Chemical Calculations of Ruthenium Nitrosyl Complexes with Tetradentate Macrocyclic Ligands

The geometric structure of the ground state and of metastable isomers of nitrosyl complexes trans-[Ru(P)(NO)(Cl)] (P = porphinate dianion) and trans-[Ru(NO)(salen)(X)]^q [salen = N,N'-ethylenebis(salicylideniminate) dianion; X = Cl^- (q = 0), H₂O (q = +1)] was optimized within the framework of the density functional method (SVWN/LanL2DZ+6-31G). The local minima corresponding to metastable isomers with a linear NO coordination through the oxygen atom and with a side ² NO coordination were found on the potential energy surfaces of these compounds. The second metastable states of all the three complexes have a lower energy. The difference in energies between the stable and metastable isomers is the least in the case of the complex trans-[Ru(NO)(salen)(Cl)].     

Semiempirical calculations of the electronic spectra of organometallic compounds: Estimation of solvent and counterion effects

The electronic spectra of the [Ru(NH₃)₅pz]²⁺, [Ru(NH₃)₅pz]³⁺, and [Ru(CN)₅pz]³⁻ complexes are calculated by the CI INDO method. The effect of solvation on the spectra is considered in a point charge approximation and in terms of the parametric model of a charged sphere enveloping the metal fragment. Interrelation of these approaches is discussed. Data on the molecular electrostatic potentials created by the complexes are presented to substantiate the models. St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 4, pp. 603–618, July–August, 1996. Translated by I. Izvekova     

Chemistry of Polypyridine Ruthenium Complexes: VII. Electronic Structure and Photochemistry of cis-[Ru(2,2'-bpy)2(L)(Cl)]+ Complexes

The electronic absorption spectra and photochemical behavior of the complexes of cis-[Ru(bpy)₂ · (L)(Cl)]⁺ (bpy is 2,2'-bipyridyl) with pyridine (L = py) and 4-substituted pyridines [L = methyl-, amino-, and cyanopyridine, and 4,4'-bipyridyl (bipy)]. Photoirradiation of acetonitrile solutions of the complexes results in substitution of ligand L by a solvent molecule. A correlation was revealed between the photolysis quantum yield and the coordination-induced ligand L-to-metal charge transfer.