Calculation Of Geometric Parameters Research Articles

Quantum-chemical calculation of steric structure of the complexes formed at template synthesis in three-component systems of Co(II) [Ni(II), Cu(II)] ion-bithiooxamide-acetone

By means of hybrid method of the density functional B3LYP with 6-31G(d) basis set we carried out calculation of geometric parameters of Co(II), Co(III), Ni(II) and Cu(II) complexes with macrocyclic ligand formed at the template processes in the systems M(II)-dithiooxamide-acetone with NNSS-coordination of donor centers. Atomic coordinates, bond lengths, bond angles and dihedral angles in the complexes with metallochelate node MN2S2 are listed. In the cases of Ni(II) and Cu(II) this chelate node is practically planar while in the case of Co(II) is tetrahedral. An additional six-membered metallocycle formed as a result of template “stitching” is screwed and turned by enough significant angle relative to five-membered rings.

Degradation of alkyl radicals via C-H bond dissociation: Kinetic parameters and transition state geometry

Experimental data on the decomposition of alkyl radicals in the gas phase of the type RCH2C.H2 → RCH=CH2 + H. were analyzed in terms of the method of crossing parabolas. The parameters characterizing such decomposition were calculated. The activation energy Ee0 for the thermoneutral degradation reaction was shown to depend on the radical structure. The degradation of the radicals RCH2C.H2, CH2=CRC.H2, PhC.HCH2R, and CH2=C.CH2R is characterized by Ee0 = 81.6, 85.9, 85.9, and 115.2 kJ mol−1, respectively. The semiempirical algorithm for calculation of geometric parameters of the transition state for reactions of hydrogen atom addition to olefins was extended to the degradation reactions of alkyl, aminoalkyl, and ketyl radicals. The kinetic (activation energies) and geometric (interatomic distances in the transition state) reaction parameters were calculated for the decomposition reactions of various alkyl, alkylaromatic, aminoalkyl, and ketyl radicals.

Electrodynamic properties of discrete surfaces. Part 2 — Symmetric multilayer discrete-plane surfaces

The paper considers peculiarities of multilayer discrete surfaces used as antenna elements and focusing devices. Relationships for calculation of geometric parameters of such surfaces are derived. The concept of generalized Fresnel zones is introduced. Based on numerical treatment of the integral equation, the characteristics of scattered fields of these surfaces and the radiation patterns of symmetric multilayer discrete- planar surfaces are analyzed.

A new type of electron energy analyzer based on three coaxial cylindrical electrodes for Auger electron spectroscopy

A new type of an electron energy analyzer for Auger electron spectroscopy (AES) constructed in our laboratory on the basis of theoretical predictions of Menchikov is described. It consists of three coaxial cylindrical electrodes for separation of the secondary electrons emitted from the excited substrate. After a short description of the fundamentals including the electron trajectory inside an analyzer the details of calculations of geometrical parameters of our construction are presented. Based on the assumed distance from the sample to image of 200mm, an analyzer constant of 2, and theoretical energy resolution of 0.03%, the entrance angle of an analyzer was calculated as α=33°55′±6°. Using a constructed analyzer in combination with a glancing incidence (15°) scanning electron gun, the Auger electron carbon C-272eV peak was recorded for the chemically etched Si(111) substrate in the EN(E) mode and then numerically differentiated to the EdN(E)/dE in order to test the possibility of the constructed AES-TCMA spectrometer for Auger line shape analysis.

Role of steric factors in formation of O?H...M hydrogen bonds with metallocenes

Molecular mechanics calculations of geometric parameters and energies of molecular complexes with a O-H...M hydrogen bond have been performed for osmocene and decamethylosmocene with three proton donors. The results of calculations demonstrated that when rings are methylated, steric hindrances to formation of this hydrogen bond increase. This is the reason for anomalously low formation constants of H-bonded Cp2*M molecular associates compared to CP2M associates.

Processing echocardiography results with microcalculators

Ultrasound diagnostics in cardiology is associated with the necessity of time-consuming calculations of geometric parameters of the left ventricle. These calculations can be considerably reduced by the doctor using commercially available unfunded microcalculators, such as MK-56. Limited memory capacity of these microcalculators (99 commands) predetermined the creation of a library of self-applied programs.

The scaled one-electron Hamiltonian model for open-shelllcao-mo-scf calculations: further corrections to thesoeh energy

The wavefunction generated by the scaled one-electron Hamiltonian (soeh) model has been modified further by including all single excitations from the space of thesoeh function. A perturbation-variation ansatz has been invoked for obtaining the corresponding energy correction (ΔE 2). [E(soeh)+ΔE 2] is shown to reproduceE(Roothaan) very closely. It has been demonstrated that by making ΔE 2 stationary with respect to change in μ results. The correctedsoeh [E(soeh)+ΔE 2] is shown to be quite useful for the calculation of geometrical parameters of open-shell systems even though it lacks the ‘upper-boundedness’ exhibited byE(soeh).

Optimal relationships between geometric parameters of a high-capacity holographic digital memory

A generalization is made of the methods for calculating geometric parameters of a high-capacity holographic digital memory. The generalization is based on the principles of geometric optics and theory of diffraction. Optimal relationships are obtained between the geometric parameters of the memeory. These relationships can be used to calculate the maximum total capacity for given dimensions and, conversely, the minimum dimensions for a given total capacity (this ensures also the maximum information density in the hologram). Examples of calculations of geometric parameters of optimized memories of this kind are given.