First Principles Molecular Simulations of Soda-Lime-Silica Glass

2008 ◽  
Vol 39-40 ◽  
pp. 85-88 ◽  
Author(s):  
Jan Macháček ◽  
Soňa Charvátová ◽  
Ondrej Gedeon ◽  
Marek Liška
Keyword(s):  
First Principles ◽  
Md Simulation ◽  
Soda Lime ◽  
Md Simulations ◽  
Distribution Functions ◽  
Basis Set ◽  
Ab Initio Molecular Dynamics ◽  
Radial Distribution Functions ◽  
Coordination Numbers ◽  
Soda Lime Silica Glass

This work aims to explore possible applications of the ab initio molecular dynamics (MD) in modeling of the soda-lime-silica (NCS) glass and melt doped with admixtures. Preparation of the basic glass (15.8 wt.% Na2O, 10.5 wt.% CaO, and 73.7 wt.% SiO2) by the MD simulation from scratch is described. The structure analysis of the NCS glass is presented in the form of total and partial radial distribution functions (RDF), coordination numbers, and fractions of Qn units. The reasonable first neighbor distances were obtained, even if a rather small basis set of electronic wavefunctions and softer pseudopotentials for atomic core regions were applied. All major discrepancies in the first neighbor distances can be easily explained, and the results can be improved if needed. The Qn distribution shows higher disproportionation of Q3 than NMR and Raman experimental data, however, it is lower than previous classical MD simulations.

scholarly journals Cholesterol Sequestration by Xenon Leads to Lipid Raft Destabilization

2020 ◽  
Author(s):  
A.D. Reyes-Figueroa ◽  
Mikko Karttunen ◽  
J.C. Ruiz-Suárez
Keyword(s):  
Virial Coefficients ◽  
Md Simulations ◽  
Distribution Functions ◽  
Coarse Grained ◽  
Unexpected Result ◽  
Radial Distribution Functions ◽  
Second Virial Coefficients ◽  
Spontaneous Nucleation ◽  
The Stability ◽  
Anaesthetic Effect

Combined coarse-grained (CG) and atomistic molecular dynamics (MD) simulations were performed to study the interactions of xenon with model lipid rafts consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) and cholesterol (Chol). At a concentration of 2 Xe/lipid we observed an unexpected result: Spontaneous nucleation of Xe nanoclusters which then rapidly plunged into the bilayer. In this process Chol, essential for raft stabilization, was pulled out from the raft into the hydrophobic zone. When concentration was further increased (3 Xe/lipid), the clusters disrupted both the membrane and raft. We computed the radial distribution functions, pair-wise potentials, second virial coefficients and Schlit-ter entropy to scrutinize the nature of the interactions. Our findings suggest that the well-known anaesthetic effect of Xe could be mediated by sequestration of Chol, which, in turn, compromises the stability of rafts where specialized proteins needed to produce the nervous signal are anchored.

OBTAINING COORDINATION NUMBERS FROM EELFS SPECTRA

1997 ◽  
Vol 04 (05) ◽  
pp. 951-954 ◽  
Author(s):  
D. V. SURNIN ◽  
D. E. DENISOV ◽  
YU. V. RUTS
Keyword(s):  
Fine Structure ◽  
Energy Loss ◽  
Electron Energy ◽  
Structural Information ◽  
Quantitative Information ◽  
Distribution Functions ◽  
Radial Distribution Functions ◽  
Regularization Algorithm ◽  
Coordination Numbers ◽  
Electron Energy Loss

The electron energy loss fine structure (EELFS) method allows one to obtain information on atomic bond lengths from the surface to the bulk. But gaining more complete quantitative information for example on coordination numbers has not presently been realized. The possibility of obtaining normalized radial distribution functions (RDF's) is shown for EELFS spectra which may be used for deriving complete structural information on pure elements. RDF's were obtained by using the regularization algorithm (after A. N. Tikhonov). The method for obtaining the RDF's was applied to the experimental Fe M 2,3 EELFS spectrum.

Spin-state dependence of the structural and vibrational properties of solvated iron(ii) polypyridyl complexes from AIMD simulations: II. aqueous [Fe(tpy)2]Cl2

2019 ◽  
Vol 21 (2) ◽  
pp. 650-661 ◽  
Author(s):  
Latévi M. Lawson Daku
Keyword(s):  
Hydration Shell ◽  
State Dependence ◽  
Distribution Functions ◽  
Water Molecules ◽  
Radial Distribution Functions ◽  
Spin States ◽  
Polypyridyl Complexes ◽  
Coordination Numbers ◽  
A Chain ◽  
First Hydration Shell

LS and HS Fe–O radial distribution functions and running coordination numbers for aqueous [Fe(tpy)2]Cl2: in both spin states, the first hydration shell of [Fe(tpy)2]2+ consists in a chain of ∼15 hydrogen-bonded water molecules wrapped around the ligands.

scholarly journals Spin-state dependence of the structural and vibrational properties of solvated iron(ii) polypyridyl complexes from AIMD simulations: III. [Fe(tpen)]Cl2 in acetonitrile

RSC Advances ◽  
2020 ◽  
Vol 10 (71) ◽  
pp. 43343-43357
Author(s):  
Latévi M. Lawson Daku
Keyword(s):  
Spin State ◽  
Radial Distribution ◽  
State Dependence ◽  
Distribution Functions ◽  
Vibrational Properties ◽  
Radial Distribution Functions ◽  
Polypyridyl Complexes ◽  
Coordination Numbers ◽  
Solvation Structure

AIMD study of the SCO [Fe(tpen)]2+ complex in acetonitrile: radial distribution functions and running coordination numbers characterizing its solvation structure in the HS state.

Structural properties of amorphous aluminum and aluminum-nitrogen alloys. Computer simulations

2004 ◽  
Vol 848 ◽  
Author(s):  
Ariel A. Valladares ◽  
Alexander Valladares ◽  
R. M. Valladares ◽  
A. Calles
Keyword(s):  
Physical Properties ◽  
Computer Simulations ◽  
First Principles ◽  
Hard Sphere ◽  
Distribution Functions ◽  
Radial Distribution Functions ◽  
Semiconducting Materials ◽  
Atomic Structures ◽  
Lennard Jones ◽  
Nitrogen Alloy

AbstractLiquid and amorphous metallic systems have proven difficult to model. Some efforts have relied on the use of parameterized classical potentials of the Lennard-Jones type or geometric hard sphere simulations, but first principles approaches have been rarely used. Clearly a knowledge of atomic structures is paramount for calculating physical properties. In this work we apply our recently developed ab initio DFT approach (A. A. Valladares et al., Eur. Phys. J. 22 (2001) 443) for the generation of amorphous semiconducting materials, to amorphize aluminum and an aluminum-nitrogen alloy. We report radial distribution functions (RDFs) and specific atomic structures of periodic amorphous/liquid cubic supercells of 108 atoms with a volume of (12.1485 Å)3, generated using the Harris functional.

scholarly journals Dynamic and Static Properties of Aqueous NaCl Solutions at 25°C as a Function of NaCl Concentration: A Molecular Dynamics Simulation Study

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Song Hi Lee
Keyword(s):  
Molecular Dynamics ◽  
Radial Distribution ◽  
Dynamic Properties ◽  
Md Simulations ◽  
Distribution Functions ◽  
Molar Conductivity ◽  
Dynamics Simulation ◽  
Radial Distribution Functions ◽  
Deep Minimum ◽  
Nacl Concentration

We present the result of molecular dynamics (MD) simulations to calculate the molar conductivity Λ m =   λ N a + +   λ C l − of NaCl in SPC/E water at 25°C as a function of NaCl concentration (c) using Ewald sums employing a velocity Verlet algorithm. It is found that the MD result for Λm with Ewald sum parameter κ = 0.10 Å−1 gives the closest one to the experimental data and that the obtained radial distribution functions g i i (r) with κ = 0.10 Å−1 show a dramatic change with a very deep minimum of g NaCl (r) and, as a result, sharp maxima of g NaNa (r) and g ClCl (r) at the distance 9.95 Å, which indicates a characteristic of ionic atmosphere, the basis of the Debye–Hückel theory of ionic solutions. The static and dynamic properties of NaCl (aq) solutions are analyzed in terms of radial distribution functions, hydration numbers, coordination numbers around Na+ and Cl−, residence times of water around Na+ and Cl−, water diffusion, and ion-ion electrostatic energies to explain the behavior of the molar conductivity Λm of NaCl obtained from our MD simulations.

Interference and Radial Distribution Functions of Liquid Copper, Silver, Tin, and Mercury

1965 ◽  
Vol 20 (3) ◽  
pp. 325-335 ◽  
Author(s):  
C. N. J. Wagner ◽  
H. Ocken ◽  
M. L. Joshi
Keyword(s):  
Radial Distribution ◽  
Liquid Copper ◽  
Pulse Height ◽  
Distribution Functions ◽  
Radial Distribution Functions ◽  
Interatomic Distances ◽  
X Ray ◽  
Coordination Numbers ◽  
X Ray Scattering ◽  
Good Agreement

The x-ray scattering from liquid copper, silver, tin, and mercury was measured at temperatures of 1125°C, 1050°C, 335°C, and 28°C, respectively, from the open surface of horizontal samples using a focusing theta-theta diffractometer, quartz crystal monochromator positioned in the diffracted beam, scintillation detector, and pulse height discriminator. The effect on the measured intensities of the positioning of the sample with respect to the diffractometer axis and the meniscus of the liquid were considered. Calibration of the primary beam intensity by measurements on liquid mercury provided an alternate check of the standard normalization procedures for copper, silver, and tin. After calculation of the interference functions, atomic and radial distribution functions were evaluated from which interatomic distances and coordination numbers were obtained. The interatomic distances in the liquid were in good agreement with the GOLDSCHMIDT diameters of the respective elements.

scholarly journals Molecular dynamic simulation study of molten cesium

2017 ◽  
Vol 82 (6) ◽  
pp. 681-694 ◽  
Author(s):  
Saeid Yeganegi ◽  
Vahid Moeini ◽  
Zohreh Doroodi
Keyword(s):  
Internal Pressure ◽  
Diffusion Coefficients ◽  
Distribution Functions ◽  
Radial Distribution Functions ◽  
Coordination Numbers ◽  
Self Diffusion ◽  
Temperature And Pressure ◽  
Molecular Dynamic Simulation Study ◽  
Dynamics Simulations ◽  
And Diffusion

Molecular dynamics simulations were performed to study thermodynamics and structural properties of expanded caesium fluid. Internal pressure, radial distribution functions (RDFs), coordination numbers and diffusion coefficients have been calculated at temperature range 700?1600 K and pressure range 100?800 bar. We used the internal pressure to predict the metal?non-metal transition occurrence region. RDFs were calculated at wide ranges of temperature and pressure. The coordination numbers decrease and positions of the first peak of RDFs slightly increase as the temperature increases and pressure decreases. The calculated self-diffusion coefficients at various temperatures and pressures show no distinct boundary between Cs metallic fluid and its expanded fluid where it continuously increases with temperature.

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