Quantum Chemical Investigations of Clusters of Heavy Metal Atoms

2016 ◽  
pp. 41-62
Author(s):  
Florian Weigend
Keyword(s):  
Heavy Metal ◽  
Quantum Chemical ◽  
Metal Atoms

A synchrotron X-ray study of the electron density in C-type rare earth oxides

1996 ◽  
Vol 52 (3) ◽  
pp. 414-422 ◽  
Author(s):  
E. N. Maslen ◽  
V. A. Streltsov ◽  
N. Ishizawa
Keyword(s):  
Heavy Metal ◽  
Rare Earth ◽  
Electron Density ◽  
Approximate Symmetry ◽  
Data Set ◽  
X Ray ◽  
Metal Atoms ◽  
Structure Factors ◽  
Deformation Electron Density ◽  
Synthetic Crystals

Structure factors for small synthetic crystals of the C-type rare earth (RE) sesquioxides Y2O3, Dy2O3 and Ho2O3 were measured with focused λ = 0.7000 (2) Å, synchrotron X-radiation, and for Ho2O3 were re-measured with an MoKα (λ = 0.71073 Å) source. Approximate symmetry in the deformation electron density (Δρ) around a RE atom with pseudo-octahedral O coordination matches the cation geometry. Interactions between heavy metal atoms have a pronounced effect on the Δρ map. The electron-density symmetry around a second RE atom is also perturbed significantly by cation–anion interactions. The compounds magnetic properties reflect this complexity. Space group Ia{\bar 3}, cubic, Z = 16, T = 293 K: Y2O3, Mr = 225.82, a = 10.5981 (7) Å, V = 1190.4 (2) Å3, Dx = 5.040 Mg m−3, μ 0.7 = 37.01 mm−1, F(000) = 1632, R = 0.067, wR = 0.067, S = 9.0 (2) for 1098 unique reflections; Dy2O3, Mr = 373.00, a = 10.6706 (7) Å, V = 1215.0 (2) Å3, Dx = 8.156 Mg m−3, μ 0.7 = 44.84 mm−1, F(000) = 2496, R = 0.056, wR = 0.051, S = 7.5 (2) for 1113 unique reflections; Ho2O3, Mr = 377.86, a = 10.606 (2) Å, V = 1193.0 (7) Å3, Dx = 8.415 Mg m−3, μ 0.7 = 48.51 mm−1 F(000) = 2528, R = 0.072, wR = 0.045, S = 9.2 (2) for 1098 unique reflections of the synchrotron data set.

scholarly journals Ruderman–Kittel–Kasuya–Yosida-type interfacial Dzyaloshinskii–Moriya interaction in heavy metal/ferromagnet heterostructures

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Taehyun Kim ◽  
In Ho Cha ◽  
Yong Jin Kim ◽  
Gyu Won Kim ◽  
Andrey Stashkevich ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Exchange Coupling ◽  
Spin Orbit Coupling ◽  
Conduction Electrons ◽  
Indirect Exchange ◽  
Metal Atoms ◽  
Technological Potential ◽  
Interfacial Modification ◽  
Coupling Phenomena ◽  
Moriya Interaction

AbstractThe manipulation of magnetization with interfacial modification using various spin-orbit coupling phenomena has been recently revisited due to its scientific and technological potential for next-generation memory devices. Herein, we experimentally and theoretically demonstrate the interfacial Dzyaloshinskii–Moriya interaction characteristics penetrating through a MgO dielectric layer inserted between the Pt and CoFeSiB. The inserted MgO layer seems to function as a chiral exchange interaction mediator of the interfacial Dzyaloshinskii–Moriya interaction from the heavy metal atoms to ferromagnet ones. The potential physical mechanism of the anti-symmetric exchange is based on the tunneling-like behavior of conduction electrons through the semi-conductor-like ultrathin MgO. Such behavior can be correlated with the oscillations of the indirect exchange coupling of the Ruderman–Kittel–Kasuya–Yosida type. From the theoretical demonstration, we could provide approximate estimation and show qualitative trends peculiar to the system under investigation.

scholarly journals Correction: Towards accurate and precise positions of hydrogen atoms bonded to heavy metal atoms

2021 ◽  
Author(s):  
Magdalena Woińska ◽  
Michał L. Chodkiewicz ◽  
Krzysztof Woźniak
Keyword(s):  
Heavy Metal ◽  
Hydrogen Atoms ◽  
Metal Atoms

Correction for ‘Towards accurate and precise positions of hydrogen atoms bonded to heavy metal atoms’ by Magdalena Woińska et al., Chem. Commun., 2021, 57, 3652–3655, DOI: 10.1039/D0CC07661A.

scholarly journals Synthesis, Characterization of a New Polyacrylic Acid Superabsorbent, Some Heavy Metal Ion Sorption, the Adsorption Isotherms, and Quantum Chemical Investigation

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4390
Author(s):  
Sevil Savaskan Yilmaz ◽  
Nuri Yildirim ◽  
Murat Misir ◽  
Yasin Misirlioglu ◽  
Emre Celik
Keyword(s):  
Heavy Metal ◽  
Quantum Chemical ◽  
Metal Ion ◽  
Molecular Mechanic ◽  
Ion Concentration ◽  
Heavy Metal Ion ◽  
Competitive Sorption ◽  
Cross Linker ◽  
The Cross

Poly(acrylic acid/Kryptofix 23-Dimethacrylate) superabsorbent polymer [P (AA/Kry23-DM) SAP] was synthesized by solution polymerization to remove Co, Ni, Cu, Cd, Mn, Zn, Pb, Cr, and Fe ions in water and improve the quality of the water. Kry23-DM cross-linker (1,4,7,13,16-Pentaoxa-10,19 diazo cyclohexene icosane di methacrylate) was synthesized using Kry23 and methacryloyl chloride. The characterization of the molecules was done by FTIR, TGA, DSC, and SEM techniques. The effects of parameters such as pH, concentration, and the metal ion interaction on the heavy metal ions uptaking of SAP was investigated. It was observed that P (AA/Kry23-DM) SAP has maximum water absorption, and the absorption increases with the pH increase. Adsorption rates and sorption capacity, desorption ratios, competitive sorption (qcs), and distribution coefficient (log D) of P(AA/Kry23-DM) SAP were studied as a function of time and pH with the heavy metal ion concentration. Langmuir and Freundlich isotherms of the P (AA/Kry23-DM) SAP were investigated to verify the metal uptake. Molecular mechanic (MM2), Assisted Model Building with Energy Refinement (AMBER), and optimized potentials for liquid simulations (OPLS) methods. were used in quantum chemical calculations for the conformational analysis of the cross-linker and the SAP. ΔH0f calculations of the cross-linker and the superabsorbent were made using Austin Model 1(AM1) method.

scholarly journals Diacetate Cellulose-Silicon Bionanocomposite Adsorbent for Recovery of Heavy Metal Ions and Benzene Vapours: An Experimental and Theoretical Investigation

2021 ◽  
Vol 12 (3) ◽  
pp. 2862-2880
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Quantum Chemical ◽  
Heavy Metal Ions ◽  
Density Functional ◽  
Basis Sets ◽  
Chemical Calculation ◽  
Quantum Chemical Analysis ◽  
The Density Functional Theory ◽  
Adsorption Capacitance

The diacetate cellulose-silicon bionanocomposite adsorbent (DACSBNC) was first introduced to recover heavy metal ions and benzene vapors. The adsorption thermodynamics of heavy metal ions and benzene vapors on the DACSBNC was first investigated by the adsorption-calorimetric, X-ray, and theoretical methods. The observed results confirmed that (i) the adsorption capacitance of DACSBNC for cadmium (II), mercury (II), and lead (II) ions were accounted for 12.23, 13.87, and 31.40 mg/g, respectively; (ii) the sorption capacitance of DACSBNC for benzene vapors was 0.5618 mmol/g. The quantum chemical calculation was also carried out on the density functional theory (DFT) using the 6-31G (d, p)/B3LYP basis sets in Gaussian 09. The results of the quantum chemical analysis support the experimental results.

Protein Visualization with Crystal Contrast

1976 ◽  
Vol 34 ◽  
pp. 486-487
Author(s):  
R. L. Hines
Keyword(s):  
Heavy Metal ◽  
Single Crystal ◽  
Biological Molecules ◽  
Single Crystal Film ◽  
Metal Atoms ◽  
Crystal Film ◽  
Contrast Mechanism ◽  
Good Contrast

Good contrast can be obtained for unstained protein in biological molecules when the molecules are supported on top of a single crystal film oriented so as to strongly diffract the illumination electrons. If the objective aperture excludes the diffracted beam, the strongly diffracting regions in the crystal film will show up in the image as dark bands a micron or more wide known as bend contours. The bend contour width is determined by the wrinkling of the crystal film which causes local changes in the crystal support film orientation. Biological molecules viewed near bend contours show contrast at exact focus without requiring staining or shadowing with heavy metal atoms. The bend contours are easily moved around by tilting the sample with a tilt stage so that it is not difficult to orient the crystal support so that it is strongly diffracting where ever the biological molecules are located on the support film. The details of the contrast mechanism have been discussed by Hines and Howie.

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