The average bond length in Pd clusters Pdn, n=4–309: A density-functional case study on the scaling of cluster properties

2001 ◽  
Vol 115 (5) ◽  
pp. 2082-2087 ◽  
Author(s):  
Sven Krüger ◽  
Stefan Vent ◽  
Folke Nörtemann ◽  
Markus Staufer ◽  
Notker Rösch
Keyword(s):  
Bond Length ◽  
Density Functional ◽  
Average Bond Length ◽  
Cluster Properties ◽  
Pd Clusters ◽  
Average Bond

Lithium and sodium diffusion in solid electrolyte materials of AM2(PO4)3(A = Li, Na, M = Ti, Sn and Zr)

2014 ◽  
Vol 28 (26) ◽  
pp. 1450176 ◽  
Author(s):  
J. J. Shi ◽  
G. Q. Yin ◽  
L. M. Jing ◽  
J. Guan ◽  
M. P. Wu ◽  
...  
Keyword(s):  
Bond Length ◽  
Density Functional ◽  
Diffusion Barriers ◽  
Average Bond Length ◽  
Elastic Band ◽  
Functional Theory ◽  
Good Potential ◽  
Na Ions ◽  
Sodium Diffusion ◽  
Average Bond

Electrolytes with a high ionic conductivity are the prerequisite for the success of solid state rechargeable ion batteries. In this paper, density functional theory (DFT) calculations are applied in combination with a climbing-image nudged elastic band (CI-NEB) method to obtain the diffusion barriers of the lithium (Li) and sodium (Na) in stoichiometric AM 2( PO 4)3 (A = Li, Na, M = Ti, Sn and Zr) compounds. In the AM 2( PO 4)3, Li and Na ions occupy the interstitial sites, M1, which is coordinated by a trigonal antiprism of oxygen, and M2, which has a distorted eight-fold coordination. Results show that the diffusion barriers are closely related with the average bond length of A–O bond when the atom A occupies the M2 site in the AM 2( PO 4)3 compounds, and the diffusion barriers decrease with increasing the average bond length. Among the various types of the AM 2( PO 4)3 compounds, the AM 2( PO 4)3 has a good potential for solid electrolytes due to its low diffusion barriers for the Li and Na.

scholarly journals 1,2,3,4,5,6,7,8,13,13,14,14-Dodecachloro-1,4,4a,4b,5,8,8a,12b-octahydro-1,4:5,8-dimethanotriphenylene at 90 K

2012 ◽  
Vol 68 (8) ◽  
pp. o2538-o2538
Author(s):  
Brandon W. Jenkins ◽  
Frank R. Fronczek ◽  
Steven F. Watkins
Keyword(s):  
Crystal Structure ◽  
Bond Length ◽  
Title Compound ◽  
Room Temperature ◽  
Bond Angle ◽  
Average Bond Length ◽  
Volume Contraction ◽  
Compound C ◽  
Independent Unit ◽  
Average Bond

The previously reported room-temperature crystal structure [Jaud Baldy, Negrel, Poite & Chanon (1993).Z. Kristallogr.204, 289–291] of the title compound, C20H8Cl12, is monoclinic withZ′ = 1, whereas the 90 K structure reported herein is triclinic withZ′ = 2 and shows a 2% volume contraction. The crystallographically independent unit chosen consists of both enantiomers (Λ and Δ) of this propeller-like molecule. Both enantiomers display quasi-twofold symmetry, with average bond-length/bond-angle deviations of 0.0018 (4) Å and 0.41 (2)° for Λ, and 0.0026 (4) Å and 0.50 (2)° for Δ.

A contribution to the structure of coals from x-ray diffraction studies

1960 ◽  
Vol 252 (1019) ◽  
pp. 557-602 ◽  
Keyword(s):  
Bond Length ◽  
Structural Model ◽  
Structural Parameters ◽  
Amorphous Material ◽  
Average Bond Length ◽  
Size Distributions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural Differences ◽  
Average Bond

Detailed X-ray diffraction studies have been carried out on a series of vitrains, anthracites, lignites, durains, fusains and certain coal extracts, of varying rank. The results are interpreted in terms of a basic structural model in which the carbon atoms are arranged in small aromatic layers linked to each other by aliphatic or alicyclic material or by five-membered rings to form large buckled sheets. Data have been obtained on the layer size distributions, the average layer diameters, the average bond length, the proportion of amorphous material and on the nature of the packing. The significance of the various structural parameters deduced from X-ray data is discussed critically. All the results are considered together in an attempt to develop as detailed a structural model as possible. The nature of the coalification process and the structural differences between various macerals are discussed and the results are compared with those deduced from other studies.

Die Kristallstruktur von Bis-[methylammonium]-hexafluorosilikat, (MeNH3)2SiF6 / The Crystal Structure of Bis-[methylammonium]-hexafluorosilicate, (MeNH3)2SiF6

2002 ◽  
Vol 57 (9) ◽  
pp. 1003-1007 ◽  
Author(s):  
Jens Graulich ◽  
Dietrich Babel
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Bond Length ◽  
Structure Determination ◽  
Average Bond Length ◽  
Space Group ◽  
X Ray ◽  
Average Bond

The results of a single crystal X-ray structure determination of monoclinic (MeNH3)2SiF6 are reported: a = 962.3(5), b = 964.4(1), c = 966.4(5) pm, " = 100.03(3)°; V = 883.2(7) Å3, Z = 4, space group C2/c; wR2 = 0.0999 based on F02 of 1291 independent reflections (including H refinement without restrictions). The structure is related to that of (NH4)2SiF6, but contains the dumb-bells of the cations well oriented along the greater cell diagonals and fixed by one nearly linear and two bi-furcated hydrogen bonds (N...F: 281 and 293 - 305 pm, resp.). The [SiF6]2- octahedron is nearly undistorted with average bond length Si-F: 167.7 pm (169.9 pm corrected for thermal motion)

scholarly journals Role of Potassium Substitution in the Magnetic Properties and Magnetocaloric Effect in La0.8−xKxBa0.05Sr0.15MnO3 (0 ≤ x ≤ 0.20)

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 407 ◽  
Author(s):  
Dhawud Sabilur Razaq ◽  
Budhy Kurniawan ◽  
Dicky Rezky Munazat ◽  
Kazumitsu Watanabe ◽  
Hidekazu Tanaka
Keyword(s):  
Bond Length ◽  
Bond Angle ◽  
Sol Gel ◽  
Double Exchange ◽  
Entropy Change ◽  
Average Bond Length ◽  
Rhombohedral Structure ◽  
Sem Images ◽  
Average Grain Size ◽  
Average Bond

The magnetic and magnetocaloric effects of potassium-substituted La0.8−xKxBa0.05Sr0.15MnO3 (0 ≤ x ≤ 0.20) manganite were explored. The samples in polycrystalline form were synthesized by the sol–gel method, with a final sintering temperature of 1100 °C. Powder X-ray diffraction (XRD) patterns refined by Rietveld refinement show that all samples crystallized in rhombohedral structure with R-3c space group. The unit cell volume of the samples decreases with increasing potassium concentration. In addition, small changes in average bond length and bond angle are also observed in the samples. Scanning electron microscope (SEM) images reveal that the largest average grain size was observed for x = 0.10. Field-cooled (FC) magnetization measurements show that the Curie temperature ( T C ) of the samples increases from 320 K for x = 0 to 360 K for x = 0.2. The largest magnetocaloric (MCE) effect, which is represented by maximum magnetic entropy change (− Δ S M , M A X ), reaches its greatest value for the x = 0.10 sample. The monotonous increase in T C suggests that TC is mainly governed by the ferromagnetic coupling between Mn ions induced by the changes on average bond length and bond angle. The obtained − Δ S M , M A X value suggests that MCE property is more sensitive to Zener theory of double exchange, which is strongly related to the Mn3+/Mn4+ ratio of the samples.

Tuning Transition Metal Carbides Activity by Surface Metal Alloying: Case Study on CO2 Capture and Activation

2018 ◽  
Author(s):  
Marti Lopez ◽  
Luke Broderick ◽  
John J Carey ◽  
Francesc Vines ◽  
Michael Nolan ◽  
...  
Keyword(s):  
Transition Metal ◽  
Co2 Capture ◽  
Density Functional ◽  
Deep Understanding ◽  
Metal Carbides ◽  
Transition Metal Carbides ◽  
Adsorption Sites ◽  
Surface Metal ◽  
A Minor

<div>CO2 is one of the main actors in the greenhouse effect and its removal from the atmosphere is becoming an urgent need. Thus, CO2 capture and storage (CCS) and CO2 capture and usage (CCU) technologies are intensively investigated as technologies to decrease the concentration</div><div>of atmospheric CO2. Both CCS and CCU require appropriate materials to adsorb/release and adsorb/activate CO2, respectively. Recently, it has been theoretically and experimentally shown that transition metal carbides (TMC) are able to capture, store, and activate CO2. To further improve the adsorption capacity of these materials, a deep understanding of the atomic level processes involved is essential. In the present work, we theoretically investigate the possible effects of surface metal doping of these TMCs by taking TiC as a textbook case and Cr, Hf, Mo, Nb, Ta, V, W, and Zr as dopants. Using periodic slab models with large</div><div>supercells and state-of-the-art density functional theory based calculations we show that CO2 adsorption is enhanced by doping with metals down a group but worsened along the d series. Adsorption sites, dispersion and coverage appear to play a minor, secondary constant effect. The dopant-induced adsorption enhancement is highly biased by the charge rearrangement at the surface. In all cases, CO2 activation is found but doping can shift the desorption temperature by up to 135 K.</div>

Pros and cons of time-dependent hybrid density functional approach to optical spectra of solids: a case study of CeO2

2021 ◽  
Author(s):  
Huai-Yang Sun ◽  
Shuo-Xue Li ◽  
Hong Jiang
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Computational Cost ◽  
Optical Spectra ◽  
First Principles Calculation ◽  
Many Body ◽  
Many Body Perturbation Theory ◽  
Pros And Cons ◽  
Hybrid Density Functional

Prediction of optical spectra of complex solids remains a great challenge for first-principles calculation due to the huge computational cost of the state-of-the-art many-body perturbation theory based GW-Bethe Salpeter equation...

CH2O Adsorption on M (M = Li, Mg and Al) Atom Deposited ZnO Nano-Cage: DFT Study

2018 ◽  
Vol 786 ◽  
pp. 384-392 ◽  
Author(s):  
Hussein Y. Ammar
Keyword(s):  
Density Functional Theory ◽  
Bond Length ◽  
Density Functional ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Structural And Electronic Properties ◽  
Formaldehyde Molecule ◽  
Electronic Configurations ◽  
Adsorption Energies ◽  
Homo Lumo

The structural and electronic properties of Li, Mg and Al deposited ZnO nanocages and their effects on the adsorption of formaldehyde molecule have been investigated using the density functional theory (DFT) computations. To understand the behavior of the adsorbed CH2O molecule on the ZnO nanocage, results of DFT calculations of the M-deposited nanocages (M=Li, Mg and Al), as well as complex systems consisting of the adsorbed CH2O molecule on M-deposited ZnO nanocage were reported. The results presented include adsorption energies, bond lengths, electronic configurations, density of states and molecular orbitals. It was found that, the most energetically stable adsorption configurations of CH2O molecule on the bare ZnO leads to 12% dilation in C=O bond length of CH2O and 14% decrease in HOMO-LUMO gap of ZnO cluster. The most energetically stable adsorption configurations of CH2O molecule on Li, Mg and Al-deposited ZnO lead to 4%, 4% and 11% dilation in C=O bond length of CH2O and-0.66, -45 and , +66% change in HOMO-LUMO gap of ZnO nanocages, respectively. The interaction between CH2O with bare ZnO and M-deposited ZnO nanocages is attributed to charge transfer mechanism. These results may be meaningful for CH2O degradation and detection.

scholarly journals Theoretical Study of Solvent Effects on the Electronic and Thermodynamic Properties of Tetrathiafulvalene (TTF) Molecule Based on DFT

2021 ◽  
pp. 42-54
Author(s):  
Rabiu Nuhu Muhammad ◽  
N. M. Mahraz ◽  
A. S Gidado ◽  
A. Musa
Keyword(s):  
Thermodynamic Properties ◽  
Bond Length ◽  
Density Functional ◽  
Theoretical Study ◽  
Energy Gap ◽  
Basis Set ◽  
Basis Sets ◽  
Frontier Molecular Orbital ◽  
Orbital Energy ◽  
Chemical Hardness

Tetrathiafulvalene () is an organosulfur compound used in the production of molecular devices such as switches, sensors, nonlinear optical devices and rectifiers. In this work, a theoretical study on the effects of solvent on TTF molecule was investigated and reported based on Density Functional Theory (DFT) as implemented in Gaussian 03 package using B3LYP/6-31++G(d,p) basis set. Different solvents were introduced as a bridge to investigate their effects on the electronic structure. The HUMO, LUMO, energy gap, global chemical index, thermodynamic properties, NLO and DOS analysis of the TTF molecule in order to determine the reactivity and stability of the molecule were obtained. The results obtained showed that the solvents have effects on the electronic and non-linear-optical properties of the molecule. The optimized bond length revealed that the molecule has strong bond in gas phase with smallest bond length of about 1.0834Å than in the rest of the solvents. It was observed that the molecule is more stable in acetonitrile with HOMO-LUMO gap and chemical hardness of 3.6373eV and 1.8187eV respectively. This indicates that the energy gap and chemical hardness of TTF molecule increases with the increase in polarity and dielectric constant of the solvents. The computed results agreed with the results in the literature. The thermodynamics and NLO properties calculation also indicated that TTF molecule has highest value of specific heat capacity (Cv), total dipole moment () and first order hyperpolarizability () in acetonitrile, while acetone has the highest value of entropy and toluene has a slightly higher value of zero point vibrational energy (ZPVE) than the rest of the solvents. The results show that careful selection of the solvents and basis sets can tune the frontier molecular orbital energy gap of the molecule and can be used for molecular device applications.

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