scholarly journals Diffusion of fructose in water: a molecular dynamics study

2020 ◽  
pp. 30-44
Author(s):  
Santosh Bhusal ◽  
Nurapati Pantha
Keyword(s):  
Molecular Dynamics ◽  
Mole Fraction ◽  
Diffusion Coefficients ◽  
Mean Square Displacement ◽  
The Self ◽  
Arrhenius Behavior ◽  
Binary Diffusion ◽  
Self Diffusion ◽  
Water Solvent ◽  
Binary Diffusion Coefficients

Present work carries the molecular dynamics (MD) simulation to study the self-diffusion coefficients of fructose (C6H12O6) and SPC/E (Extended Simple Point Charge) water (H2O) along with their binary diffusion coefficients at different temperature (298.15 K, 303.15 K, 308.15 K and 312.15 K). A dilute solution of 3 molecules of fructose (solute, mole fraction 0.0018) and 1624 molecules of water (solvent, mole fraction 0.9982) has been taken for making it relevant to the previously reported experiment. The structural analysis of the mixture has been estimated by using the radial distribution function (RDF) of its constituents. Mean square displacement (MSD) and Einstein’s relation have been used to find the self-diffusion coefficients of both the solute and solvent. Furthermore, Darken’s relation finds the binary diffusion coefficients. The temperature dependence of diffusion coefficients follows the Arrhenius behavior which further calculates activation energy of diffusion. The results from the present work agree well with the previously reported experimental values.

Diffusion coefficients of nitric oxide in water: A molecular dynamics study

2016 ◽  
Vol 30 (27) ◽  
pp. 1650205 ◽  
Author(s):  
Sunil Pokharel ◽  
Nurapati Pantha ◽  
N. P. Adhikari
Keyword(s):  
Nitric Oxide ◽  
Molecular Dynamics ◽  
Mole Fraction ◽  
Diffusion Coefficients ◽  
Low Temperatures ◽  
Mean Square Displacement ◽  
Mutual Diffusion ◽  
Arrhenius Behavior ◽  
Self Diffusion ◽  
Experimental Values

Self-diffusion coefficients along with the mutual diffusion coefficients of nitric oxide (NO) and SPC/E water (H2O) as solute and solvent of the mixture, have been studied within the framework of classical molecular dynamics level of calculations using GROMACS package. The radial distribution function (RDF) of the constituent compounds are calculated to study solute–solute, solute–solvent and solvent–solvent molecular interactions as a function of temperature. A dilute solution of five NO molecules (mole fraction 0.018) and 280 H2O molecules (mole fraction 0.982) has been taken as the sample. The self-diffusion coefficient of the solvent is calculated by using mean square displacement (MSD) where as that for solute (NO) is calculated by using MSD and velocity auto-correlation function (VACF). The results are then compared with the available experimental values. The results from the present work for water come in good agreement, very precise at low temperatures, with the experimental values. The diffusion coefficients of NO, on the other hands, agree well with the available theoretical studies, and also with experiment at low temperatures (up to 310 K). The results at the higher temperatures (up to 333 K), however, deviate significantly with the experimental observations. Also, the mutual diffusion coefficients of NO in water have been calculated by using Darken’s relation. The temperature dependence of the calculated diffusion coefficients follow the Arrhenius behavior.

Molecular dynamics study of diffusion of krypton in water at different temperatures

2016 ◽  
Vol 30 (11) ◽  
pp. 1650064 ◽  
Author(s):  
Dipendra Bhandari ◽  
N. P. Adhikari
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Mean Square Displacement ◽  
Mutual Diffusion ◽  
Arrhenius Behavior ◽  
Self Diffusion ◽  
Velocity Autocorrelation ◽  
Different Temperatures ◽  
Self Diffusion Coefficient

Molecular dynamics study of diffusion of two krypton atoms in 300 SPC/E water molecules at temperatures 293, 303, 313, 323 and 333 K has been carried out. Self-diffusion coefficient of krypton and water along with their mutual diffusion coefficients are estimated. Self-diffusion coefficient for krypton is calculated by using Mean Square Displacement (MSD) method and Velocity Autocorrelation (VACF) method, while that for water is calculated by using MSD method only. The mutual diffusion coefficient is estimated by using the Darken’s relation. The diffusion coefficients are found to follow the Arrhenius behavior. The structural properties of the system have been estimated by the study of solute–solute, solvent–solvent, and solute–solvent Radial Distribution Function (RDF).

Molecular-Dynamics Analysis of the Structural Properties of Silica during Cooling

2008 ◽  
Vol 139 ◽  
pp. 101-106 ◽  
Author(s):  
Byoung Min Lee ◽  
Shinji Munetoh ◽  
Teruaki Motooka ◽  
Yeo Wan Yun ◽  
Kyu Mann Lee
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Transition Temperature ◽  
Structural Properties ◽  
Diffusion Coefficients ◽  
The Self ◽  
Dynamics Analysis ◽  
Self Diffusion ◽  
Dynamics Simulations ◽  
Potential Parameters

The structural properties of SiO2 liquid during cooling have been investigated by molecular dynamics simulations. The interatomic forces acting on the particles are calculated by the modified Tersoff potential parameters. The glass transition temperature and structural properties of the resulting SiO2 system at various temperatures have been investigated. The fivefold coordinations of Si and threefold coordinations of O atoms were observed, and the coordination defects of system decrease with decreasing temperature up to 17 % at 300 K. The self-diffusion coefficients for Si and O atoms drop to almost zero below 3000 K. The structures were distorted at high temperatures, but very stable atomic network persisted up to high temperature in the liquid state.

The Concentration Dependences of the Binary Diffusion Coefficients of the Systems H2–Ne, D2–Ne, H2–N2, D2–N2, H2–Ar, and D2–Ar at 1 Atm Pressure and 300 K

1972 ◽  
Vol 50 (14) ◽  
pp. 1644-1647 ◽  
Author(s):  
K. R. Harris ◽  
T. N. Bell ◽  
Peter J. Dunlop
Keyword(s):  
Mole Fraction ◽  
Diffusion Coefficients ◽  
Experimental Error ◽  
Similar Data ◽  
Enskog Theory ◽  
Intermolecular Potentials ◽  
Binary Diffusion ◽  
Concentration Dependences ◽  
Binary Diffusion Coefficients

Binary diffusion coefficients have been measured as a function of concentration for the systems H2–Ne, D2–Ne, D2–N2, H2–Ar, and D2–Ar at 1 atm pressure and 300 K. Similar data have already been presented for the system H2–N2. As predicted by the Chapman–Enskog theory, the concentration dependences of the diffusion coefficients for the systems containing deuterium are somewhat less than for the corresponding systems containing hydrogen. The data for the systems containing Ne and N2 indicate that there may be differences between the parameters required to describe the assumed spherical intermolecular potentials for the systems H2–Ne and D2–Ne, and also for the systems H2–N2 and D2–N2. The concentration dependences of the diffusion coefficients of all six systems are, within the estimated experimental error of ±0.2%, linear in the mole fraction of the heavier component in each system, x2.

A Molecular Dynamics Simulation of Molten (Li-Rb)Cl Implying the Chemla Effect of Mobilities

1980 ◽  
Vol 35 (5) ◽  
pp. 493-499 ◽  
Author(s):  
Isao Okada ◽  
Ryuzo Takagi ◽  
Kazutaka Kawamura
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Diffusion Coefficients ◽  
Strong Correlation ◽  
Pair Correlation ◽  
The Self ◽  
Dynamics Simulation ◽  
Self Diffusion ◽  
Pure Salt ◽  
Dynamics Simulations

Abstract A new transport property, the self-exchange velocity (SEV) of neighbouring unlike ions, has been evaluated from molecular dynamics simulations of molten LiCl, RbCl and LiRbCl2 at 1100 K and the mixture at 750 K. From the increase of the SEV's in the order Rb+ (pure salt) <Li+ (mixture) < Rb+ (mixture) < Li+ (pure salt), it is conjectured that there is a strong correlation between the SEV’s and the internal mobilities. An interpretation of the Chemla effect in its dependence on temperature is given. The pair correlation functions and the self-diffusion coefficients are also calculated and discussed.

The Concentration Dependence at 1 atm Pressure and 300 °K of the Binary Diffusion Coefficients of the Systems Helium – Carbon Dioxide, Helium – Nitrous Oxide, and Helium – Sulfur Hexafluoride

1972 ◽  
Vol 50 (12) ◽  
pp. 1874-1876 ◽  
Author(s):  
Kenneth R. Harris ◽  
T. N. Bell ◽  
Peter J. Dunlop
Keyword(s):  
Carbon Dioxide ◽  
Nitrous Oxide ◽  
Diffusion Coefficient ◽  
Concentration Dependence ◽  
Mole Fraction ◽  
Diffusion Coefficients ◽  
Sulfur Hexafluoride ◽  
Enskog Theory ◽  
Binary Diffusion ◽  
Binary Diffusion Coefficients

Binary diffusion coefficients are reported for the systems He–CO2, He–N2O, and He–SF6. In agreement with the Chapman–Enskog theory the concentration dependence of the diffusion coefficient of each system increases with the mole fraction of the heavier component.

scholarly journals Molecular-Dynamics Simulation of Self-Diffusion of Molecular Hydrogen in X-Type Zeolite

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaoming Du
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
Hydrogen Diffusion ◽  
Mean Free Path ◽  
The Self ◽  
Dynamics Simulation ◽  
Pulse Field ◽  
Self Diffusion ◽  
Hydrogen Molecules ◽  
Dynamics Simulations

The self-diffusion of hydrogen in NaX zeolite has been studied by molecular-dynamics simulations for various temperatures and pressures. The results indicate that in the temperature range of 77–293 K and the pressure range of 10–2700 kPa, the self-diffusion coefficients are found to range from 1.61 × 10−9 m2·s−1to 3.66 × 10−8 m2·s−1which are in good agreement with the experimental values from the quasielastic neutron scattering (QENS) and pulse field gradients nuclear magnetic resonance (PFG NMR) measurements. The self-diffusion coefficients decrease with increasing pressure due to packing of sorbate-sorbate molecules which causes frequent collusion among hydrogen molecules in pores and increase with increasing temperature because increasing the kinetic energy of the gas molecules enlarges the mean free path of gas molecule. The activated energy for hydrogen diffusion determined from the simulation is pressure-dependent.

scholarly journals Molecular Dynamics Study of Hydrogen on Alkali-Earth Metal Cations Exchanged X Zeolites

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Du Xiaoming
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
Knudsen Diffusion ◽  
Earth Metal ◽  
The Self ◽  
Pulse Field ◽  
Self Diffusion ◽  
Hydrogen Molecules ◽  
X Zeolites ◽  
Diffusion Of Hydrogen

The self-diffusion of hydrogen in Ca2+-, Mg2+- and Ba2+-exchanged X zeolites (Mg46X, Ca46X, and Ba46X) has been studied by molecular dynamics (MD) simulations for various temperatures and loadings. The results indicate that in the temperature range of 77–298 K and the loading range of 1–80 molecules/cell, the self-diffusion coefficients are found to range from1.2×10-9 m2·s−1to2.3×10-7 m2·s−1which are in good agreement with the experimental values from the quasielastic neutron scattering (QENS) and pulse field gradients nuclear magnetic resonance (PFG NMR) measurements. The self-diffusion coefficients decrease with loading due to packing of sorbate-sorbate molecules which causes frequent collusion among hydrogen molecules in pores and increases with increasing temperature because increasing the kinetic energy of the gas molecules enlarges the mean free path of gas molecule. The mechanism of diffusion of hydrogen molecules in these zeolites is transition diffusion. Knudsen diffusion occurs at low loading and the molecular bulk diffusion occurs at higher loading. For given temperature and loading, the self-diffusion coefficients decrease in the orderBa46X<Mg46X<Ca46X, due to the different sizes and locations of the divalent cations. Moreover, the effect of concentration of molecular hydrogen on self-diffusion coefficient also is analyzed using radial distribution function (RDF).

Computer Simulation of Diffusion of Pb-Bi Eutectic in Liquid Sodium by Molecular Dynamics Method

2002 ◽  
Author(s):  
Yingxia Qi ◽  
Minoru Takahashi
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Process ◽  
Diffusion Coefficients ◽  
The Self ◽  
Molecular Dynamics Method ◽  
Pure Liquid ◽  
Empirical Equations ◽  
Potential Candidate ◽  
Self Diffusion ◽  
Dynamics Method

Lead-bismuth eutectic is a potential candidate for coolant of secondary loops of sodium-cooled fast breeder reactors (FBR). The studies on the diffusion of liquid Pb-Bi in liquid Na are carried out corresponding to the case that liquid Pb-Bi leaks to liquid Na by accident. As the diffusion processes are the results of atomic motions, molecular dynamics method has been used to study the diffusion process. The self-diffusion coefficients of pure liquid Pb and Na, and liquid Pb-Bi are calculated and compared with ones by the empirical equations. The discrepancy between them could be eliminated by changing the densities of the liquids. The diffusion of lead-bismuth in sodium is simulated based on the changed densities under which the self-diffusion coefficients of individual liquid metals are close to those by the empirical equations. The simulation results show that the diffusion process of liquid Pb-Bi in liquid Na is a heat releasing process and the density of ternary liquid Na-Pb-Bi is higher than the average value of the densities of liquid Na and liquid Pb-Bi. It is also found that the diffusion coefficients of liquid Pb-Bi in liquid Na are much higher than their self-diffusion coefficients, indicating that liquid Pb-Bi are easy and quickly to diffuse in liquid Na. However, the diffusion coefficient of liquid Na is decreased due to the existence of liquid Pb-Bi, implying that liquid Na-Pb-Bi have a higher viscosity than that of pure liquid Na.

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