scholarly journals Quantum-Chemical Design of Molecular Structures of Tetra-, Penta- and Hexanuclear Metal Clusters Containing Aluminum and 3d-Element Atoms

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1852
Author(s):  
Oleg V. Mikhailov ◽  
Denis V. Chachkov
Keyword(s):  
Ground State ◽  
Quantum Chemical ◽  
Metal Clusters ◽  
Complex Dynamics ◽  
Thermodynamic Characteristics ◽  
Molecular Structures ◽  
Spin Multiplicity ◽  
Structural Isomers ◽  
The Individual ◽  
The Given

Various data on the structural and thermodynamic characteristics of polynuclear metal clusters containing atoms of aluminum and various d-elements with the general formula AlnMm where (n + m) is 4, 5, or 6, and which can be precursors for the formation of nanoparticles of elemental metals or intermetallic compounds, have been systematized and discussed. It has been noted that each of these metal clusters in principle is able to exist in very diverse structural isomers, differing significantly among themselves in terms of the total energy and spin multiplicity of the ground state, the number of which is determined by both the specific values of n and m, and the nature of d-elements in their compositions. The presence of very complex dynamics with respect to the changes of the individual thermodynamic characteristics of the metal clusters under consideration as well as the thermodynamic parameters of the reactions of their formation, depending on the nature of the d-element, were also ascertained. In the main, the given review is devoted to the authors’ works published over the last 10 years. Bibliography – 96 references.

scholarly journals Quantum-Chemical Consideration of Al2M2 Tetranuclear Metal Clusters (M–3d-Element): Molecular/Electronic Structures and Thermodynamics

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6836
Author(s):  
Oleg V. Mikhailov ◽  
Denis V. Chachkov
Keyword(s):  
Electronic Structures ◽  
Quantum Chemical ◽  
Metal Clusters ◽  
Molecular Structures ◽  
Chemical Calculation ◽  
Geometric Form ◽  
Structural Isomers ◽  
Torsion Angles ◽  
Homo And Lumo ◽  
The Given

Quantum-chemical calculation of most important parameters of molecular and electronic structures of tetra-nuclear (pd) metal clusters having Al2M2 composition, where M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, or Zn (bond lengths, bond and torsion angles), and HOMO and LUMO of these compounds by means of DFT OPBE/QZVP method, have been carried out. It has been found that, for each of these metal clusters, an existence of rather large amount of structural isomers different substantially in their total energy, occurs. It has been noticed that molecular structures of metal clusters of the given type differ significantly between them in terms of geometric parameters, as well as in geometric form, wherein the most stable modifications of metal clusters considered are similar between themselves in geometric form. In addition, the standard thermodynamic parameters of formation of metal clusters considered here, and namely standard enthalpy ΔfH0(298 K), entropy Sf0(298 K), and Gibbs’ energy ΔfG0(298 K) of formation for these metal clusters, were calculated.

scholarly journals Models of Molecular Structures of Hexa-Nuclear AlnFem Metal Clusters (n + m = 6): DFT Quantum-Chemical Design

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 597
Author(s):  
Oleg V. Mikhailov ◽  
Denis V. Chachkov
Keyword(s):  
Quantum Chemical ◽  
Density Functional ◽  
Metal Clusters ◽  
Dft Method ◽  
Molecular Structures ◽  
Dihedral Angles ◽  
Geometric Form ◽  
Structural Isomers ◽  
Functional Theory ◽  
The Density Functional Theory

By using the density functional theory (DFT) method at the OPBE/QZVP level, key parameters of molecular structures of six-atomic (heterobi)nuclear metal clusters with an AlnFem composition (n + m = 6) (bond lengths, bond angles, and torsion (dihedral) angles) were calculated. It was found that each of these clusters exists in a large number of structural isomers that differ substantially in terms of their total energy. Furthermore, the molecular structures of these structural isomers significantly differ regarding the geometric parameters and geometric form. In addition, the most stable structural isomers of these metal clusters also differ rather considerably in terms of the geometric form.

scholarly journals Theoretical Simulation of the Zeke Spectra of Naphthalene From Single Vibronic Levels of S1

1999 ◽  
Vol 19 (1-4) ◽  
pp. 105-108 ◽  
Author(s):  
Fabrizia Negri ◽  
Marek Z. Zgierski
Keyword(s):  
Ab Initio ◽  
Quantum Chemical Calculations ◽  
Ground State ◽  
Quantum Chemical ◽  
Electronic States ◽  
Perturbative Expansion ◽  
Molecular Structures ◽  
Theoretical Simulation ◽  
Vibronic States ◽  
Semi Empirical

We present the simulations and analysis of the two-color ZEKE spectra of naphthalene, performed with the help of quantum chemical calculations of molecular parameters followed by the modelling of vibronic intensities. Ab initio and semi-empirical calculations were carried out to obtain molecular structures of neutral and ionic naphthalene, and vibronic perturbations that couple the electronic states. It is shown that the intensities, simulated with a model based on the perturbative expansion of vibronic states, nicely reproduce the observed spectra and contribute to reassign some of the ground state frequencies of naphthalene cation.

Structural Isomers of C70

1992 ◽  
Vol 270 ◽  
Author(s):  
Krishnan Raghavachari
Keyword(s):  
Ab Initio ◽  
Ground State ◽  
Quantum Chemical ◽  
Energy Difference ◽  
Structural Isomers ◽  
Chemical Techniques ◽  
Isomeric Structures

ABSTRACTAlternative isomeric structures of C70 have been investigated using semiempirical and ab initio quantum chemical techniques. As in the case of C60, these isomers are characterized by the presence of pentagonal rings adjacent to each other. The lowest energy alternative isomer of C70 has only one pair of edge-sharing pentagons and lies ≈ 1.4 eV higher in energy than the ground state. This energy difference is smaller than that for the lowest energy alternative isomer of C60 which contains two pairs of adjacent pentagons and lies ≈ 2.0 eV higher in energy than its ground state.

Novel oxidation state — zinc(III) in chelate with 3,7,11,15-tetraazaporphine and one fluorine ligand: Quantum-chemical modeling

2019 ◽  
Vol 23 (06) ◽  
pp. 685-689 ◽  
Author(s):  
Oleg V. Mikhailov ◽  
Denis V. Chachkov
Keyword(s):  
Oxidation State ◽  
Quantum Chemical Calculation ◽  
Ground State ◽  
Quantum Chemical ◽  
Structural Parameters ◽  
Dft Method ◽  
Fluoride Ion ◽  
Chemical Calculation ◽  
Chemical Modeling ◽  
The Given

Based on the results of a quantum chemical calculation using the DFT method, the possibility of the existence of a zinc heteroligand complex with 3,7,11,15-tetraazaporphine and fluoride ion with an oxidation state of Zn(III), unusual for the given element, is shown. Data on the structural parameters and multiplicity of the ground state of this complex are also presented.

Defective Buckyballs: Alternative Structural Isomers of C60

1992 ◽  
Vol 247 ◽  
Author(s):  
Krishnan Raghavachari ◽  
Celeste M. Rohlfing
Keyword(s):  
Ab Initio ◽  
Ground State ◽  
Quantum Chemical ◽  
Structural Isomers ◽  
Chemical Techniques

ABSTRACTAlternative isomerie structures of C60 spheroids have been investigated using semiempirical and ab initio quantum chemical techniques. Unlike the icosahedral ground state, these isomers are characterized by the presence of pentagonal rings adjacent to each other. The lowest energy alternative isomer of C60 has two such pairs of edge-sharing pentagons and lies = 2 eV higher in energy than the ground state. Isomers containing three and four pairs of adjacent pentagons have also been studied in detail. Overall, the energy contributions of these adjacent pentagonal defects are additive, with each defect making the structure less stable by = 1 eV.

Application of the turbidity ratio method in the spherical particle size determination in the range m ∈ and α ∈

1979 ◽  
Vol 44 (7) ◽  
pp. 2064-2078 ◽  
Author(s):  
Blahoslav Sedláček ◽  
Břetislav Verner ◽  
Miroslav Bárta ◽  
Karel Zimmermann
Keyword(s):  
Refractive Index ◽  
Spherical Particle ◽  
Ratio Method ◽  
Refractive Indices ◽  
Relative Refractive Index ◽  
Particle Size Determination ◽  
The Individual ◽  
The Given ◽  
Turbidity Ratio ◽  
Selection Of

Basic scattering functions were used in a novel calculation of the turbidity ratios for particles having the relative refractive index m = 1.001, 1.005 (0.005) 1.315 and the size α = 0.05 (0.05) 6.00 (0.10) 15.00 (0.50) 70.00 (1.00) 100, where α = πL/λ, L is the diameter of the spherical particle, λ = Λ/μ1 is the wavelength of light in a medium with the refractive index μ1 and Λ is the wavelength of light in vacuo. The data are tabulated for the wavelength λ = 546.1/μw = 409.357 nm, where μw is the refractive index of water. A procedure has been suggested how to extend the applicability of Tables to various refractive indices of the medium and to various turbidity ratios τa/τb obtained with the individual pairs of wavelengths λa and λb. The selection of these pairs is bound to the sequence condition λa = λ0χa and λb = λ0χb, in which b-a = δ = 1, 2, 3; a = -2, -1, 0, 1, 2, ..., b = a + δ = -1, 0, 1, 2, ...; λ0 = λa=0 = 326.675 nm; χ = 546.1 : 435.8 = 1.2531 is the quotient of the given sequence.

Solvation of ions by dipolar aprotic solvents and water. A CNDO/2 study

1985 ◽  
Vol 50 (11) ◽  
pp. 2493-2508 ◽  
Author(s):  
Petr Kyselka ◽  
Zdeněk Havlas ◽  
Ivo Sláma
Keyword(s):  
Binary Mixtures ◽  
Quantum Chemical ◽  
Chemical Method ◽  
Molecular Structures ◽  
Dimethyl Sulphoxide ◽  
Ternary Mixtures ◽  
Aprotic Solvents ◽  
Quantum Chemical Method ◽  
Solvation Of Ions ◽  
Dipolar Aprotic Solvents

Solvation of Li+, Be2+, Na+, Mg2+, and Al3+ ions has been studied in binary mixtures with dimethyl sulphoxide, dimethylformamide, acetonitrile and water, and in ternary mixtures of the organic solvents with water. The CNDO/2 quantum chemical method was used to calculate the energies of solvation, molecular structures and charge distributions for the complexes acetonitrile...ion (1:1, 2:1, 4:1), dimethyl sulphoxide...ion (1:1), dimethylformamide...ion (1:1), and acetonitrile (dimethyl sulphoxide, dimethylformamide)...ion...water (1:1:1).

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