Atomic structure

Zeolites, commonly referred to as molecular sieves, are aluminosilicate minerals with an open structure and interconnecting holes that can be explored by molecular, atomic, and ionic components. Zeolites, called pozzolans, are hydrophilic aluminum silicates that contain alkali and alkaline earth elements.

7p viyoko 01-10-2024 2 2   Download

This global minimum structure has the shape of a tetragonal bipyramid having two Sc atoms at two tops of pyramids binding with one edge of Ge-Ge. The ground electronic state of the global minimum isomer is the 2B2 state in the C2v symmetry. The most stable isomer of Sc2Ge6 − has been used to study the CO adsorption. The calculated results indicate that the Sc2Ge6 − cluster has a good interaction with the CO molecule. The adsorption positions are around the Sc atom with two stable models include adsorbing the C atom and adsorbing both the C and O atoms of the CO molecule.

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This article presents computational insights into the geometric and electronic structures of NbSi4 −/0 clusters using density functional theory and the CASSCF/CASPT2 method. The anionic and neutral ground states are identified as the 1A′ and 2A′ states, respectively, within a trigonal bipyramidal isomer where the Nb atom occupies the equatorial position. The adiabatic detachment energy for the transition from the anionic ground state 1A′ to the neutral ground state 2A′ is estimated to be 2.30 eV.

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The geometric structure, stability, dissociation channel and magnetism of AgnCo clusters (n = 1–12) have been studied using density functional theory. The results show that the Co atom tends to choose the highest coordination position.

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The analytic expressions of the free energy, the mean nearest neighbor distance between two atoms, the elastic moduli such as the Young modulus E, the bulk modulus K, the rigidity modulus G and the elastic constants C11, C12, C44 for substitution alloy AB with interstitial atom C and BCC structure under pressure are derived from the statistical moment method.

12p vijichoo2711 04-06-2021 16 1   Download

Thermodynamic quantities such as mean nearest neighbor distance, free energy, isothermal and adiabatic compressibilities, isothermal and adiabatic elastic modulus, thermal expansion coefficient, heat capacities at constant volume and constant pressure, and entropy of binary interstitial alloys with a body-centered cubic (BCC) structure with a very small concentration of interstitial atoms are derived using the statistical moment method.

10p tamynhan5 10-12-2020 17 3   Download

At a temperature of 300 K, both Ni and Cu atoms are crystallized into the face-centered cubic (FCC) and the hexagonal close-packed (HCP) phases, respectively. The mechanical characteristics of the sample at 300 K were also analyzed in detail through the determination of elastic modulus, number of atoms, and void distribution during the tensile process.

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Protein is composed of amino acids which are, in turn, made up of mostly carbon, hydrogen, oxygen, nitrogen. A protein structure consists of thousands of coordinates of its atoms. Building structure index tables (often organized by suffix trees or arrays) of proteins is an important phase for quickly searching or classifying protein structures.

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The coefficients of thermal expansion of thin metal film with face-centered cubic structure at zero pressure are investigated using the statistical moment method (SMM), including the anharmonic effects of thermal lattice vibration. The Helmholtz free energy, mean-square atomic displacement and linear thermal expansion coefficients are derived in closed analytic forms in terms of the power moments of the atomic displacement.

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In this research, the structural and electronic properties of N-doped anatase TiO2 layers were evaluated using the density functional theory (DFT). The results show that doping positions of N atoms cause different effects on the size and shape of unit cells of models.

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This paper studies the structure of the Mullite system (3Al2O3.2SiO2) by Molecular Dynamics simulation (MDs) using the Born–Mayer–Huggins pair interaction and periodic boundary conditions. The simulation was performed with model of 5250 atoms at different pressure and at 3500 K temperature.

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To clarify the local environment of atoms, we apply the oxygen simplex (OS) which is characterized by the size, forming oxygen atom types and the number of sodium atoms located inside the OS. The simulation shows that the liquid comprises the Si-O network and sodium atoms are distributed through different OS types forming by four O atoms.

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In present paper, we will present the theory of elastic deformation for binary interstitial alloys with FCC structure at zero pressure and under pressure builded by the SMM. Then, we apply this theory to study the elastic deformation of interstitial alloy AgC by combining the Mie-Lennard-Jones pair potential [14] and the Morse pair potential.

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Analytical expressions for the anharmonic effective potential, local force constant, Displacement-displacement Correlation Function (DCF) CR and Debye-Waller factor described by the Mean Square Relative Displacement (MSRD) σ2 and by the Mean Square Displacement (MSD) u2of bcc crystals in the X-ray Absorption Fine Structure (XAFS) have been derived. The effective interatomic potential of the system has been considered by taking into account the influences of nearest atomic neighbors, and it contains the Morse potential characterizing the interaction of each pair of atoms.

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In this study, we report the vibrational infrared spectra of most stable SinMn2+ clusters (n=5–9) using density functional theory calculations. An attempt has been made to theoretically construct infrared spectra of the investigated clusters in case of more than one stable isomers coexisting. The finding results would serve as fringerprints for further structural identification of interested clusters.

8p abcxyz123_02 03-03-2020 26 3   Download

The reliability of Quantitative Structure – Activity or Property Relationships for prediction of physico-chemical properties and anticancer activity of flavone and isoflavone derivatives was improved by using the quantitative relationships between structurally similar flavone and isoflavone structures (QSSRs). The targeted-compound method was developed by a training set, which contains only similar compounds structurally to target compound.

7p nguathienthan1 20-11-2019 22 2   Download

In present work, the formation constants, logb110, logb120 and the concentration of [M] and [MLi ] in complex solutions of Cu2+ and the amino acids were determined by using the quantitative electron structure and properties relationships (QESPRs) and quantitative complex and complex relationships (QCCRs). The relative charge nets for complex structures were calculated by using molecular mechanics MM+ and semiempirical quantum chemistry calculations ZINDO/1. The QESPRs and QCCRs models were constructed by the atomic charge net on complex structures and the multivariate regression analysis.

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A benzothiazolium-derived colorimetric and fluorescent chemosensor (L) for detection of mercury ions has been prepared. The detection limits of the colorimetric and fluorescent method for mercury ions are 15.3 and 11.8 ppb, respectively, much lower than the reported chemosensors based on similar derivatives of benzothiazolium.

7p lamtan3547 04-11-2018 38 1   Download

Hydrotalcite-type (HT) materials based on ZnAlO and MgAlO have been prepared and investigated by various physico-chemical method: IR, XRD, BET... It was found that the HT structure depended on the nature and the atom ratio of the metals. The adsorption ability of the materials was tested with the reactive dyes Red 3BA as a model compound. The results indicated that the materials with the HT structure and atom ratio of Me2+ /Me3+ = 3 : 1 calcinated at < 500o C have the highest dyes removal. That could be related with the chemical characterization.

5p uocvong04 24-09-2015 79 5   Download

2D nanomaterials such as graphene and transition metal dichal  cogenides (TMDCS) have shown outstanding potential in many fields such as fl exible electronics, sensing and optics due to their desirable physical and structural properties. High quality black phosphorus atomic layers by liquid phase exfoliation include Experimental Section; Supporting Information and Acknowledgements.

6p dangthaitrieu 11-05-2015 34 3   Download