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Article
Possibilities of Quantum-Chemical Modeling of Domain Boundaries in the Cluster Approximation of the Ising Model for Materials of the Potassium Dihydrogen Phosphate Family
For potassium dihydrogen phosphate and its deuterated analogue, trial versions of model clusters have been proposed to analyze the influence of domain walls on the thermodynamic properties of these ferroelectr...
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Article
Dimensional Volume and Surface Characteristics Calculated for KDP-Type Crystals in the Lattice Gas Model with a Many-Particle Interaction Potential
An approach is formulated for calculating bulk and surface size characteristics of multidomain KDP-type crystals using the lattice gas model (LGM). Energy states of various proton configurations responsible fo...
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Article
Possibilities of a Simplified Approach to Studying the Features of Structural Phase Transitions in H-Bonded Ferroelectrics with the use of Ab Initio Calculations
Using the К(Н/D)2РО4 ferroelectrics as an example, a simplified quantum-chemical approach to the description of the structural phase transition driven by an increase in the number of H/D-bonds in model clusters h...
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Article
Dependence of the Properties of KDP-Type H-Bonded Ferroelectrics on the Cation Nature. Quantum-Chemical Modeling
The origin of cation-induced (K+ and \({\text{NH}}_{4}^{ + }\) ) differences in the character of ordering of critical ions (H/D) responsible for the ferroelectric activity of H-bonded ferroelectrics and related...
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Article
The Effect of Model Cluster Expansion on the Results of Microscopic Description of the Properties of KDP type H-Bonded Ferroelectrics
The results of model cluster expansion for qualitative description of thermodynamics of a structural phase transition and other properties and for elucidation of the effect of domain boundaries were analyzed w...
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Article
Attempt of Quantum Chemical Modeling of the Structural Phase Transition in the Quasi-One-Dimensional H-Bonded Ferroelectric Crystal of CsH2PO4 and Its Deuterated Analog CsD2PO4
Thermodynamic features of the structural phase transition in an H-bonded ferroelectric material—cesium dihydrophosphate—and its deuterated analog were studied within the pseudospin Ising model with taking into...
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Article
Quantum-Chemical Modeling of the Effect of Stretching Mechanical Activation of the Central С–С Bonds in Linear Polymers
The effect of mechanical activation by preliminarily stretching linear polymeric hydrocarbon molecules (e.g., polyethylene and polypropylene) on the energy force characteristics of the cleavage of central С‒С ...
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Article
Comparative Quantum-Chemical Analysis of the Structure and Relative Stability of Oxyanions of Main-Group Elements of the Second and Third Periods
The reasons for the difference in coordination numbers of the central atoms (E) in the oxyanions of main-group elements of the second and third periods have been considered using various quantum-chemical metho...
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Article
Quantum-Chemical Analysis of the Structural Phase Transition in Quasi–One-Dimensional Ferroelectrics Pb(H/D)PO4
The applicability of the simplest cluster models for semi-quantitative descriptions of the thermodynamics of structural phase transitions in quasi–one-dimensional ferroelectrics is considered. A lead hydrogen ...
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Article
Effect of the Hydrostatic Pressure on the Thermodynamics of Structural Phase Transition in Quasi-One-Dimensional Ferroelectrics Pb(H/D)PO4: Quantum Chemical Analysis
The change in the structural phase transition thermodynamics of lead hydrogen phosphate (LHP) and lead deuterium phosphate (LDP) depending on the external hydrostatic pressure was studied using the Ising pseud...
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Article
Quantum-chemical analysis of the thermodynamic isotope effect in quasi-one-dimensional H-bonded Pb(H/D)PO4 ferroelectrics
The thermodynamics of the structural phase transition of H-bonded ferroelectric materials, Pb(H/D)PO4, were considered in terms of the pseudo-spin Ising model with inclusion of tunneling and longrange effects. Th...
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Article
Structural phase transition in quasi-one-dimensional H-bonded ferroelectric PbHPO4 (LHP) crystal: Quantum-chemical analysis
Thermodynamic features of the structural phase transition (SPT) in the H-bonded ferroelectric material PbHPO4 (LHP) have been considered using a pseudo-spin Ising model with inclusion of tunneling and long-range ...
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Article
Quantum-chemical simulation of the elementary step of the oxidation reactions of styrene and its derivatives involving 1О2 (1Δg)
The results of simulation of the oxidation reaction of styrene and its methyl (two isomers) and phenyl derivatives with molecular oxygen in the excited singlet state (1Δg) have enabled the conclusion that the rea...
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Article
Quantum-chemical simulation of unit process for the oxidation reactions of ethylene and its derivatives invoving 1O2 (1Δg)
The results of simulation of oxidation reactions of ethylene derivatives with different substituents (F atoms, CH3O and CH3 groups) and butadiene molecule with participation of 1O2 (1Δg) have shown the possibilit...
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Article
Mechanism and energetics of 1,2-addition of dioxygen 1O2(1Δg) to ethylene
The optimal geometry and energy parameters for five electronic states of the {1O2 (1Δg) + C2H4} system that characterize the elementary reactions of two-step 1,2-addition giving the dioxetane molecule were calcul...
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Article
Contribution of vibronic interactions to the thermodynamics of the phase transition in H-bonded ferroelectrics: Proton-lattice coupling effects in crystals of the KDP family
A model Hamiltonian for microscopic description of structural phase transitions in KDP type ferroelectrics was considered in terms of the vibronic theory of heteroligand systems (VTHS). The Hamiltonian contain...
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Article
Mechanism of oxygen transfer from the vanadium(V) complexes with ligands O2 2− and O3 2−
The oxygen transfer from the vanadium(V) complexes containing peroxo, oxo, and ozonide ligands to electron-donating substrates (ethylene and vinyl methyl ether) was studied in the framework of the DFT with the...
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Article
Comparative quantum chemical study of cyclic ether-water complexes
The interaction of the cyclic ethers tetrahydrofuran (THF) and 1,4-dioxane (DO) with water molecules in 1: 1 and 1: 2 ratios and with water dimers has been investigated by the density functional theory method ...
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Article
Comparative quantum-chemical study of complexes of cyclic ether with ethylene glycol
The electronic structure and geometry of cyclic ethers—tetrahydrofuran and 1,4-dioxane—and their 1: 1 and 1: 2 complexes with ethylene glycol, as well as their complexes with ethylene glycol dimers, have been ...
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Article
Indirect non-electrostatic mechanism of the proton-proton interaction and proton-lattice coupling in KH2PO4 ferroelectrics
It has been shown that the mechanism previously proposed for the effective interaction of protons in MH2 AO4 ferroelectrics, such as KH2PO4 (KDP), is applicable to the description of the proton-la...
