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Effective Hardness of Interaction From Thermodynamics and Transport in Dilute Gases



Ian H. Bell


The hardness of the effective inverse-power-law potential, which can be obtained from thermodynamics or collision integrals, can be used to obtain a coherent means of demonstrating similarities between thermodynamics and transport. This link is investigated for systems of increasing complexity (EXP, square-well, Lennard- Jones, Stockmayer, ab initio results for small molecules, and rigid linear chains of Lennard- Jones sites). These results show that while the two approaches do not yield precisely the same values of effective inverse power law exponent, their qualitative behavior is intriguingly similar, offering a new way of understanding the effective interactions between molecules, especially at high temperatures. In both approaches, the effective hardness is obtained from a double-logarithmic temperature derivative of an effective area. At low temperatures, the hardness of the effective inverse-power-law still provides physical insights, and offers a means of understanding the appropriate behavior of virial coefficients at temperatures far below where experimental data exist.
The Journal of Chemical Physics


dilute gases, thermodynamics, transport, molecular interaction


Bell, I. (2020), Effective Hardness of Interaction From Thermodynamics and Transport in Dilute Gases, The Journal of Chemical Physics, [online], (Accessed April 14, 2024)
Created March 31, 2020, Updated July 8, 2020