Determination of the Molecular Law of Force from Self-Diffusion Coefficients

1947 ◽  
Vol 72 (7) ◽  
pp. 642-643 ◽  
Author(s):  
I. Amdur
Keyword(s):  
Diffusion Coefficients ◽  
Self Diffusion

scholarly journals Two Faces of the Two Phase Thermodynamic Model

2021 ◽  
Author(s):  
Ádám Madarász ◽  
Andrea Hamza ◽  
Dávid Ferenc ◽  
Imre Bakó
Keyword(s):  
Diffusion Coefficients ◽  
Heat Capacities ◽  
The Self ◽  
Quantum Corrections ◽  
Organic Liquids ◽  
Harmonic Model ◽  
Two Phase ◽  
Self Diffusion ◽  
Error Cancellation

<div>The quantum harmonic model and the two-phase thermodynamics method (2PT) are widely used to obtain quantum corrected properties such as isobaric heat capacities or molar entropies. 2PT heat capacities were calculated inconsistently in the literature, and the excellent correlations are due to error cancellation for organic liquids. We reanalyzed the performance of different quantum corrections on the heat capacities of common organic solvents against experimental data. The accuracy of the computations was also assessed with the determination of the self-diffusion coefficients.</div><div><br></div>

A MOLECULAR DYNAMICS STUDY OF OXYGEN GAS IN WATER AT DIFFERENT TEMPERATURES

2013 ◽  
Vol 27 (08) ◽  
pp. 1350023 ◽  
Author(s):  
S. K. THAPA ◽  
N. P. ADHIKARI
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
Distribution Functions ◽  
Self Diffusion ◽  
Water As Solvent ◽  
Different Temperatures ◽  
Oxygen Gas ◽  
Dynamics Simulations ◽  
Solvent Solvent

Molecular dynamics simulations of a binary mixture of oxygen gas and SPC/E water, with oxygen gas ( O 2) as solute and water as solvent, at oxygen mole fraction of 0.019 have been accomplished at different temperatures 288, 293, 298, 302 and 306 K using Groningen Machine for Chemical Simulations. The solvent–solvent, solute–solute and solute–solvent radial distribution functions (RDFs) have been estimated. The solvent–solvent (water–water) RDF has been found to agree with that obtained from NMR/X-ray data within 7%. Self-diffusion coefficients of both the solvent and the solute have been determined by means of mean-squared displacement curves using Einstein's relation. They are found to agree with experimental results very well. Darken's relation has also been invoked for the determination of mutual diffusion coefficients at the respective temperatures. The analysis of temperature dependence of the diffusion coefficients has revealed that they follow Arrhenius equation to a very good extent and are consistent with the nature of RDF's at the respective temperatures. The estimated activation energies are in excellent agreement with the available experimental data.

scholarly journals A New Method for Determination of Self-diffusion Coefficients in Solid Solutions

1974 ◽  
Vol 47 (3) ◽  
pp. 600-603 ◽  
Author(s):  
Seiichi Kurihara ◽  
Kazuo Fueki ◽  
Takashi Mukaibo
Keyword(s):  
Solid Solutions ◽  
Diffusion Coefficients ◽  
New Method ◽  
Self Diffusion

scholarly journals Two Faces of the Two Phase Thermodynamic Model

2021 ◽  
Author(s):  
Ádám Madarász ◽  
Andrea Hamza ◽  
Dávid Ferenc ◽  
Imre Bakó
Keyword(s):  
Heat Capacity ◽  
Diffusion Coefficients ◽  
Heat Capacities ◽  
Water Model ◽  
Organic Liquids ◽  
Harmonic Model ◽  
Two Phase ◽  
Self Diffusion ◽  
Anharmonic Correction

<div>The quantum harmonic model and the two-phase thermodynamics method (2PT) are widely used to obtain quantum corrected properties such as isobaric heat capacities or molar entropies. 2PT heat capacities were calculated inconsistently in the literature. For water the classical heat capacity was also considered, but for organic liquids it was omitted. We reanalyzed the performance of different quantum corrections on the heat capacities of common organic solvents against experimental data. We have pointed out serious flaws in previous 2PT studies. The vibrational density of states was calculated incorrectly causing 39 \% relative error in diffusion coefficients and 45 \% error in the 2PT heat capacities. The wrong conversion of isobaric isochoric heat capacity also caused about 40 \% error but in the other direction. We have introduced the concept of anharmonic correction which is simply the deviation of the classical heat capacity from that of the harmonic oscillator model. This anharmonic contribution is around +30-40 J/mol/K for water depending on the water model and -8-10 J/mol/K for hydrocarbons and halocarbons. AC is unrealistically large, +40 J/K/mol for alcohols and amines indicating some deficiency of the OPLS force field. The accuracy of the computations was also assessed with the determination of the self-diffusion coefficients.<br></div>

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