Two Faces of the Two Phase Thermodynamic Model

10.26434/chemrxiv.13643051.v1 ◽

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>

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Two Faces of the Two Phase Thermodynamic Model

10.26434/chemrxiv.13643051.v2 ◽

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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Two Faces of the Two Phase Thermodynamic Model

10.33774/chemrxiv-2021-qn3m7-v3 ◽

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

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 (AC) 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.

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Determination of the self-diffusion coefficients of gold by Autoradiography

JOM ◽

10.1007/bf03398882 ◽

1954 ◽

Vol 6 (5) ◽

pp. 616-619 ◽

Cited By ~ 2

Author(s):

Harry C. Gatos ◽

Anthony D. Kurtz

Keyword(s):

Diffusion Coefficients ◽

The Self ◽

Self Diffusion

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SELF-DIFFUSION OF RUBIDIUM AS INFLUENCED BY SOIL MOISTURE TENSION

Canadian Journal of Soil Science ◽

10.4141/cjss63-006 ◽

1963 ◽

Vol 43 (1) ◽

pp. 44-51 ◽

Cited By ~ 13

Author(s):

A. S. Patil ◽

K. M. King ◽

M. H. Miller

Keyword(s):

Diffusion Coefficient ◽

Soil Moisture ◽

Diffusion Coefficients ◽

The Self ◽

Self Diffusion ◽

Steady State Method ◽

Loam Soil ◽

Time Periods ◽

Self Diffusion Coefficient

A non steady-state method was used for the laboratory determination of the self-diffusion coefficient of rubidium in loam soil at soil moisture tensions of.16, 1.17, and 15 atmospheres. Soil volumes (half-cells) 1.0 centimeter long and 2.5 centimeters in diameter, containing rubidium labelled with Rb86, were placed in contact with similar but unlabelled half-cells. After varying time periods, the half-cells were separated and extracted with 1N NH4Ac, and the transfer of Rb86 determined.The diffusion followed the simple theory. The self-diffusion coefficients for rubidium at 25 °C. were as follows: 16 × 10−4 cm.2/hr. at 0.16 atm.; 4.9 × 10−4 cm.2/hr. at 1.17 atm.; 2.3 × 10−4 cm.2/hr. at 15 atm. In free solution, the self-diffusion coefficient is 7.2 × 10−2 cm.2/hr.

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Self-Diffusion Coefficients, Aggregation Numbers and the Range of Existence of Spherical Micelles of Oxyethylated Alkylphenols

Applied Magnetic Resonance ◽

10.1007/s00723-021-01323-4 ◽

2021 ◽

Author(s):

Victor P. Arkhipov ◽

Natalia A. Kuzina ◽

Andrei Filippov

Keyword(s):

Aqueous Solutions ◽

Diffusion Coefficients ◽

The Self ◽

Self Diffusion ◽

Aggregation Numbers ◽

Temperature Ranges ◽

Spherical Micelles ◽

Limiting Values

AbstractAggregation numbers were calculated based on measurements of the self-diffusion coefficients, the effective hydrodynamic radii of micelles and aggregates of oxyethylated alkylphenols in aqueous solutions. On the assumption that the radii of spherical micelles are equal to the lengths of fully extended neonol molecules, the limiting values of aggregation numbers corresponding to spherically shaped neonol micelles were calculated. The concentration and temperature ranges under which spherical micelles of neonols are formed were determined.

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