It is known that plastic relaxation behind the shock wave front in metals and alloys achieved through intense dislocation multiplication. Most of molecular dynamics simulations usually consider perfect crystals, which needs to be nucleated. The present paper presents dynamic loading [100], [110], [111] molybdenum crystals micrometer length, both with dislocations, over a wide range temperatures from 300 2100 K. evolution structure Hugoniot elastic limit (HEL) analyzed for dependence...

This article is devoted to a molecular dynamics simulation study of partial dislocation loop nucleation with respect its mechanism and rate, propagation process under high shear stress in aluminum-copper alloys. The mechanisms near Guinier-Preston (GP) zones various diameters concentrations have been analyzed. Dislocation rates plain GP Cu-zones 3.5, 7.5, 13.5 nm at calculated using the mean lifetime method temperatures range 100 700 K. It has found that depending on temperature applied...

The paper investigates the role of solid solution strengthening on shock wave structure and Hugoniot elastic limit (HEL) in [111] copper crystals by molecular dynamics. Cu–Ni, Cu–Zn, Cu–Ag, Cu–Al solutions are chosen to cover range atomic size misfit parameters for solute atoms. results show that with dislocations, HEL decays slower an increase parameter solute, resulting higher values at a certain propagation distance. largest exhibit deceleration decay. When concentration Al atoms...

Two possible schemes of carbonate formation (with and without water participation) in cationic form zeolites are considered. Activation energy for the hydrogen NaX zeolite from carbon dioxide is calculated at DFT level with periodic boundary conditions, while problems modeling symmetric same discussed. The copper studied using binuclear CuOCu clusters CO2 where influence on barrier questions related to application also considered by comparison data obtained MP2 level. reactivity tested...

An effect of deblocking small size (8R, D8R) pores in zeolites due to cation drift is analyzed by using ab initio molecular dynamics (AIMD) at the PBE-D2/PAW level. The carbonate and hydrocarbonate species on carbon dioxide uptake NaKA zeolite demonstrated. It shown that a or anion can form strong complexes with K+ withdraw it from 8R window, so probability CO2 diffusion through increases. For first time, correlations between cationic HCO3-/CO32- positions are demonstrated favor their...

Using atomistic calculations, we study the features of uniaxial deformation nanotubes made rolled-up thin [0 1 0] plates Fe cubic crystals. We find that within a certain range chiral angles these have both negative Poisson's ratio and axial strain-induced torsion (reverse Poynting's effect) during tension compression. The maximum minimum value are observed at [Formula: see text] text], respectively. show Young's modulus increases with angle. demonstrate in discussed nanotube sizes there is...

The decrease in elastic moduli (Young's, bulk, and shear modulus), the variations their asymmetries, Poisson's ratio linear compressibility due to carbonate formation NaX, have been compared those produced by dealumination of zeolite HY framework, from Al-Si-Al fragment positioned joined 4R rings. All these systems considered at density functional theory (DFT) level using periodic boundary conditions. representativeness models has checked comparison calculated IR spectra hydrocarbonate...

Possible mechanism of oxidative carbonylation methanol via >Cu(OCH3)2Cu< binuclear cationic oxo-clusters in the CuNaX zeolite with Cu2+ cations is analyzed theoretically within scope periodic boundary conditions VASP. Such scheme was first derived by Saegusa et al. (J. Org. Chem.1970, 35, 2976) and never tested theoretical modeling to our best knowledge. For CO attack we have computed activation energy value that close experimental values obtained Cu-zeolites. We suppose this can correctly...

Two variants of the introduction transition metals (TMs) Me = Ni, Mn, Co into Pd(100)/(100)γ-Al2O3 catalytic system are presented to reveal a possible influence TM on activity Pd for CH4 dissociation. Al/Me replacement at (100)γ-Al2O3 surface is performed normal (four-coordinated) or undercoordinated (two-coordinated) Al positions, one hand. MeAl2O4 spinel formation admitted stoichiometric Me/Al ratio, other The addition slab weakly changes activation energy dissociation barrier higher...

A series of PdO slabs deposited via low-index planes (100), (010), (001), and (101) on γ-alumina, titania, zirconia was modeled. Relative stabilities surface energies the are divided into two groups one hand, (101), other hand. The calculated barriers CH4 dissociation increase with stability or decreases versus joined system being lowest for 4-layer PdO(010) without support over monoclinic ZrO2. authors outline that oxidation upon a partial transformation Pd to allows growing more active (in...