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Thermodynamic functions as correlation-function integrals.

K Koga¹, B Widom

¹Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan. koga@okayama-u.ac.jp

The Journal of Chemical Physics

|March 29, 2013

Summary

This summary is machine-generated.

Thermodynamic functions can be expressed using correlation-function integrals. The choice of molecular centers is arbitrary, but these integrals remain independent of the choice, as shown for hard spheres and propane.

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Area of Science:

Thermodynamics
Statistical Mechanics
Physical Chemistry

Background:

Thermodynamic functions are often expressed as correlation-function integrals.
Key integrals include Ornstein-Zernike, Kirkwood-Buff, and virial coefficient formulas.
The choice of molecular centers for distance measurement is arbitrary.

Purpose of the Study:

To recall expressions of thermodynamic functions as correlation-function integrals.
To highlight the independence of these integrals from the arbitrary choice of molecular centers.
To illustrate this principle with specific examples.

Main Methods:

Recalling established integral expressions for thermodynamic functions.
Analyzing the impact of arbitrary molecular center choices on correlation functions.
Illustrating with calculations for hard spheres and propane.
Utilizing computer simulations for pair correlations in water and aqueous solutions.

Main Results:

Correlation-function integrals for thermodynamic properties are independent of the chosen molecular centers.
This independence was demonstrated for hard spheres in 1D, 2D, and 3D.
The principle was also shown for gaseous propane and simulated water systems.

Conclusions:

The arbitrariness of molecular center selection does not affect the resulting thermodynamic integrals.
This confirms the robustness of correlation-function integral methods in thermodynamics.
The findings are validated across different dimensions and molecular systems.