Book contents
- Frontmatter
- Dedication
- Contents
- List of Figures
- List of Tables
- Acknowledgements
- Nomenclature
- 1 Introduction
- 2 The Boltzmann Equation 1: Fundamentals
- 3 The Boltzmann Equation 2: Fluid Dynamics
- 4 Transport in Dilute Gas Mixtures
- 5 The Dilute Lorentz Gas
- 6 Basic Tools of Nonequilibrium Statistical Mechanics
- 7 Enskog Theory: Dense Hard-Sphere Systems
- 8 The Boltzmann–Langevin Equation
- 9 Granular Gases
- 10 Quantum Gases
- 11 Cluster Expansions
- 12 Divergences, Resummations, and Logarithms
- 13 Long-Time Tails
- 14 Transport in Nonequilibrium Steady States
- 15 What’s Next
- Bibliography
- Index
11 - Cluster Expansions
Published online by Cambridge University Press: 18 June 2021
- Frontmatter
- Dedication
- Contents
- List of Figures
- List of Tables
- Acknowledgements
- Nomenclature
- 1 Introduction
- 2 The Boltzmann Equation 1: Fundamentals
- 3 The Boltzmann Equation 2: Fluid Dynamics
- 4 Transport in Dilute Gas Mixtures
- 5 The Dilute Lorentz Gas
- 6 Basic Tools of Nonequilibrium Statistical Mechanics
- 7 Enskog Theory: Dense Hard-Sphere Systems
- 8 The Boltzmann–Langevin Equation
- 9 Granular Gases
- 10 Quantum Gases
- 11 Cluster Expansions
- 12 Divergences, Resummations, and Logarithms
- 13 Long-Time Tails
- 14 Transport in Nonequilibrium Steady States
- 15 What’s Next
- Bibliography
- Index
Summary
Symmetric functions of phase variables of N particles, can be expanded, formally, in terms of a series of Ursell cluster functions. They depend successively on one, two, ..., particle variables. For equilibrium systems, cluster expansions are used to obtain virial expansions of the thermodynamic functions, The cluster expansion method can be applied to N-particle time displacement operators and to the initial distribution function for a non-equilibrium system. Assuming a factorization property of the initial distribution function, one obtains expansions of the time dependent two and higher particle distributions in terms of successively higher products of one particle functions. This expansion of the pair distribution function, together with the first hierarchy equation generalizes the Boltzmann equation to higher densities in terms of the dynamics of successively higher number of particles considered in isolation. Contributions from correlated binary collision sequences appear and for hard spheres the Enskog equation is an approximation.
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- Information
- Contemporary Kinetic Theory of Matter , pp. 437 - 466Publisher: Cambridge University PressPrint publication year: 2021