Theoretical Insights on the High Pressure Behavior of Pentazolate Anion Complex [Co(H2O)4(N5)2]·4H2O

Abstract Periodic dispersion corrected density functional theory (DFT) calculations were carried out to examine the Hirshfeld surface, two dimensional (2D) fingerprint plots, crystal structure, molecular structure and density of state of all-nitrogen pentazolate anion complex [Co(H2O)4(N5)2]·4H2O under hydrostatic pressure from 0 to 20 GPa. The GGA/PW91-OBS method was applied in the present study. The intercontacts in [Co(H2O)4(N5)2]·4H2O were analyzed by Hirshfeld surfaces and 2D fingerprint plots. With ascending pressure, the lattice constants, compression rates, bond lengths, bond angles, and density of states change irregularly. Under 11.5, 13.0 and 15.8 GPa, covalent interaction competition is obvious between Co−N and Co−O bonds. It is possible to achieve orderly modification and regulation of the internal structure of [Co(H2O)4(N5)2]·4H2O by applied pressure. This is in accordance with the results from density of states analysis. The external compression causes the nonuniformity of electron density and the differential covalent interaction between pentazolate anion, coordinated water and atom Co. It is of great significance to interpret inter/intramolecular interaction and structural stability of [Co(H2O)4(N5)2]·4H2O and provide theoretical guidance for the design of metal complexes of all-nitrogen pentazolate anion.

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First-Principle Study on Half-Metallic Ferromagnetism and Structural Stability of C-Doped Alkaline-Earth Chalcogenides under Pressure

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1052.155 ◽

2014 ◽

Vol 1052 ◽

pp. 155-162

Author(s):

Hui Zhao ◽

Qian Han

Keyword(s):

Density Of States ◽

Density Functional ◽

Magnetic Phase ◽

Magnetic Moments ◽

Second Order ◽

Magnetic Phase Transitions ◽

First Principle ◽

Half Metallic ◽

Lattice Constants ◽

Cell Volumes

Three half-metallic ferromagnets with NaCl structure, X4CS3(X = Mg, Ca and Sr) are investigated by the first principle calculations based on the density functional theory in thegeneralized gradient approximation. Non-spin and spin polarized calculations are done to obtain the lattice constants, the equilibrium cell volumes, the stable energies and the magnetic moments of X4CS3, and band structure and density of states for X4CS3at high pressure are calculated. From the calculations it has been found that X4CS3is stable in the FM state. The corresponding lattice constants and the equilibrium cell volumes in FM are greater than that in NM. The magnetic moment of X4CS3decrease as pressure increases, and a second order magnetic phase transition of Sr4CS3from FM to NM state at pressure of 140GPa, but a second order magnetic phase transitions of Mg4CS3and Ca4CS3have not been found. According to the band and the density of states, as the pressure increases the half-metallic nature of X4CS3destroyed.

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Combined Computational and Experimental Study of the Pressure Dependence of the Structural and Vibrational Properties on Solid Naphthalene C10H8

Materials Science Forum ◽

10.4028/www.scientific.net/msf.914.175 ◽

2018 ◽

Vol 914 ◽

pp. 175-181

Author(s):

Ling Ping Xiao ◽

Li Zeng ◽

Xue Yang

Keyword(s):

Density Functional ◽

Intramolecular Interaction ◽

Applied Pressure ◽

Experimental Studies ◽

Density Functional Theory Calculations ◽

Optical Data ◽

Vibrational Properties ◽

Intermolecular Distances ◽

Almost All

We present high-quality optical data and density functional theory calculations for the structural and vibrational properties of solid naphthalene (C10H8) under pressure up to 21.5 GPa. Our results demonstrate that almost all the modes shift toward higher frequencies and some peaks are broadened with increasing pressure. Comparing the pressure effect on the shortest intermolecular distances and on the bond lengths we confirm the expected result that the intramolecular interaction are less sensitive to pressure than the intermolecular interactions. These findings are shown to be in agreement with experimental results and hint towards the evolution of intermolecular interaction with pressure. Moreover, within our data the lattice modes exhibit more drastic changes than intramolecular modes, which are due to there being greater intermolecular distortions than intramolecular under applied pressure. In combination with theoretical and experimental studies, these results permit detailed characterization of the structural and vibrational changes of naphthalene as a function of pressure.

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STRUCTURAL, ELECTRONIC AND PHONON PROPERTIES OF LaX COMPOUNDS (X = P, As)

International Journal of Modern Physics B ◽

10.1142/s0217979208049200 ◽

2008 ◽

Vol 22 (28) ◽

pp. 5027-5033 ◽

Cited By ~ 3

Author(s):

GÖKAY UǦUR ◽

ŞULE UǦUR ◽

AYTAÇ ERKIŞI ◽

FETHI SOYALP

Keyword(s):

Density Functional Theory ◽

Bulk Modulus ◽

Density Of States ◽

Density Functional ◽

Theoretical Calculations ◽

Generalized Gradient ◽

Pressure Derivative ◽

Functional Theory ◽

Lattice Constants ◽

Phonon Properties

The structural, electronic and phonon properties of the LaP and LaAs compounds in NaCl (B1) and CsCl (B2) structures are studied by means of density functional theory within the generalized gradient approximation. The calculated lattice constants, static bulk modulus and first-order pressure derivative of the bulk modulus are reported in both B1 and B2 structures and compared with previous experimental and theoretical calculations. Band structure and density of states calculations are carried out for LaP and LaAs . Then, a linear-response approach to the density functional theory is used to derive the phonon frequencies and density of states.

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Density Functional Theory Study of the Mechanical and Electronic Properties of Rutile TiO2: A Computer Simulation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.333-335.1955 ◽

2013 ◽

Vol 333-335 ◽

pp. 1955-1958

Author(s):

Chao Xu ◽

Dong Chen

Keyword(s):

Density Functional Theory ◽

Band Structure ◽

Elastic Constants ◽

Density Functional ◽

Applied Pressure ◽

Generalized Gradient ◽

Functional Theory ◽

Lattice Constants ◽

Pseudo Potential ◽

Forbidden Gap

In this paper, we investigate the structural, electronic and elastic properties of rutile using the ultra-soft pseudo-potential scheme in the framework of density functional theory, together with the generalized gradient approximation. The calculated lattice constants and elastic constants are generally consistent with the other results. Our aim is twofold. First, density functional theory is a fine theory that can obtain reliable results. Second, rutile can be used in the modern industry, thus it should be carefully investigated. The elastic constants dependences on pressure are calculated. It is found that rutile is stable in the pressure range of 020Gpa. The anisotropy of this compound increases with applied pressure. Besides, the analysis of band structure is also given. The calculated band structure shows that rutile belongs to direct-forbidden-gap semiconductors.

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Density Functional Theory Investigations of the Mechanical Properties of Anatase: A Computer Simulation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.333-335.1903 ◽

2013 ◽

Vol 333-335 ◽

pp. 1903-1906

Author(s):

Chao Xu ◽

Dong Chen

Keyword(s):

Density Functional Theory ◽

Computer Simulation ◽

Density Functional ◽

Theoretical Perspective ◽

Applied Pressure ◽

Optical Parameter ◽

Functional Theory ◽

Lattice Constants ◽

Pressure Interval ◽

Theoretical Results

The lattice parameters (lattice constants a, c), elastic properties (elastic constants, bulk modulus, shear modulus) and optical parameter (dielectric function) are investigated from a theoretical perspective using computer simulation in the frame of density functional theory. The calculated lattice constants and elastic moduli are in agreement with the theoretical results. We found that anatase can retain its stability in the pressure interval 020Gpa. The anisotropy of this compound is found to increase with applied pressure. Moreover, the dielectric functions are also discussed. The plasma frequency and static dielectric constant of TiO2 are 16eV and 6.1, respectively. * Corresponding author: Dong CHEN

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A First-Principles Computational Comparison of the Aqueous Anatase TiO2 (001) Interface and the Disordered, Fluorinated TiO2 Interface

10.26434/chemrxiv.7076816.v1 ◽

2018 ◽

Author(s):

Kyle Reeves ◽

Damien Dambournet ◽

Christel Laberty-Robert ◽

Rodolphe Vuilleumier ◽

Mathieu Salanne

Keyword(s):

Density Of States ◽

Density Functional ◽

Water Dissociation ◽

Water Molecules ◽

Chemical Doping ◽

Charge Balance ◽

Functional Theory ◽

Adsorption Of Water ◽

Properties Of Materials ◽

Computational Comparison

Chemical doping and other surface modifications have been used to engineer the bulk properties of materials, but their influence on the surface structure and consequently the surface chemistry are often unknown. Previous work has been successful in fluorinating anatase TiO2 with charge balance achieved via the introduction of Ti vacancies rather than the reduction of Ti. Our work here investigates the interface between this fluorinated titanate with cationic vacancies and a monolayer of water via density functional theory based molecular dynamics. We compute the projected density of states for only those atoms at the interface and for those states that fall within 1eV of the Fermi energy for various steps throughout the simulation, and we determine that the variation in this representation of the density of states serves as a reasonable tool to anticipate where surfaces are most likely to be reactive. In particular, we conclude that water dissociation at the surface is the main mechanism that influences the anatase (001) surface whereas the change in the density of states at the surface of the fluorinated structure is influenced primarily through the adsorption of water molecules at the surface.

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A First-Principles Computational Comparison of the Aqueous Anatase TiO2 (001) Interface and the Disordered, Fluorinated TiO2 Interface

10.26434/chemrxiv.7076816 ◽

2018 ◽

Author(s):

Kyle Reeves ◽

Damien Dambournet ◽

Christel Laberty-Robert ◽

Rodolphe Vuilleumier ◽

Mathieu Salanne

Keyword(s):

Density Of States ◽

Density Functional ◽

Water Dissociation ◽

Water Molecules ◽

Chemical Doping ◽

Charge Balance ◽

Functional Theory ◽

Adsorption Of Water ◽

Properties Of Materials ◽

Computational Comparison

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Magnetic Volume Effect of Hydrogen Diffusion in Palladium

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.310.29 ◽

2020 ◽

Vol 310 ◽

pp. 29-33

Author(s):

Sarantuya Nasantogtokh ◽

Xin Cui ◽

Zhi Ping Wang

Keyword(s):

Transition Metal ◽

Density Of States ◽

Density Functional ◽

Hydrogen Diffusion ◽

Magnetic Moments ◽

Interstitial Site ◽

Volume Effect ◽

Face Centered Cubic ◽

Hydrogen Atoms ◽

Octahedral Interstitial Site

The electronic and magnetic properties of palladium hydrogen are investigated using first-principles spin-polarized density functional theory. By studying the magnetic moments and electronic structures of hydrogen atoms diffusing in face-centered cubic structure of transition metal Pd, we found that the results of magnetic moments are exactly the same in the two direct octahedral interstitial site-octahedral interstitial site diffusion paths-i.e. the magnetic moments are the largest in the octahedral interstitial site, and the magnetic moments are the lowest in saddle point positions. We also studied on the density of states of some special points, with the result that the density of states near the Fermi level is mainly contributed by 4d electrons of Pd and the change of magnetic moments with the cell volume in the unit cell of transition metal Pd with a hydrogen atom.

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First-Principles Study of Mechanical and Thermodynamic Properties of Binary and Ternary CoX (X = W and Mo) Intermetallic Compounds

Materials ◽

10.3390/ma14061404 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1404

Author(s):

Yunfei Yang ◽

Changhao Wang ◽

Junhao Sun ◽

Shilei Li ◽

Wei Liu ◽

...

Keyword(s):

Free Energy ◽

Thermodynamic Properties ◽

Gibbs Free Energy ◽

Density Functional ◽

Vibrational Entropy ◽

Functional Theory ◽

Lattice Constants ◽

The Density Functional Theory ◽

Ductile Behavior ◽

Pseudo Potential

In this study, the structural, elastic, and thermodynamic properties of DO19 and L12 structured Co3X (X = W, Mo or both W and Mo) and μ structured Co7X6 were investigated using the density functional theory implemented in the pseudo-potential plane wave. The obtained lattice constants were observed to be in good agreement with the available experimental data. With respect to the calculated mechanical properties and Poisson’s ratio, the DO19-Co3X, L12-Co3X, and μ-Co7X6 compounds were noted to be mechanically stable and possessed an optimal ductile behavior; however, L12-Co3X exhibited higher strength and brittleness than DO19-Co3X. Moreover, the quasi-harmonic Debye–Grüneisen approach was confirmed to be valid in describing the temperature-dependent thermodynamic properties of the Co3X and Co7X6 compounds, including heat capacity, vibrational entropy, and Gibbs free energy. Based on the calculated Gibbs free energy of DO19-Co3X and L12-Co7X6, the phase transformation temperatures for DO19-Co3X to L12-Co7X6 were determined and obtained values were noted to match well with the experiment results.

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Towards an accurate description of perovskite ferroelectrics: exchange and correlation effects

Scientific Reports ◽

10.1038/srep43482 ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 21

Author(s):

Simuck F. Yuk ◽

Krishna Chaitanya Pitike ◽

Serge M. Nakhmanson ◽

Markus Eisenbach ◽

Ying Wai Li ◽

...

Keyword(s):

Density Functional ◽

General Purpose ◽

Correlation Effects ◽

Lattice Constants ◽

Bulk Solids ◽

Wide Range ◽

Exchange Enhancement ◽

Experimental Values ◽

Similar Accuracy ◽

Ferroelectric Oxides

Abstract Using the van der Waals density functional with C09 exchange (vdW-DF-C09), which has been applied to describing a wide range of dispersion-bound systems, we explore the physical properties of prototypical ABO 3 bulk ferroelectric oxides. Surprisingly, vdW-DF-C09 provides a superior description of experimental values for lattice constants, polarization and bulk moduli, exhibiting similar accuracy to the modified Perdew-Burke-Erzenhoff functional which was designed specifically for bulk solids (PBEsol). The relative performance of vdW-DF-C09 is strongly linked to the form of the exchange enhancement factor which, like PBEsol, tends to behave like the gradient expansion approximation for small reduced gradients. These results suggest the general-purpose nature of the class of vdW-DF functionals, with particular consequences for predicting material functionality across dense and sparse matter regimes.

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