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This monograph gives a comprehensive treatment of practical calculations of time correlation functions for the, study of fluid dynamics at the molecular level. Tests of the validity of such calculations are made by direct comparison of theoretical analyses and experimental data. The strength of the work lies in the range of models and theoretical methods studied and the
in-depth discussions of data interpretation. The book is organised in six chapters, which fall logically into three groups. The introduction chapter deals chiefly with motivations for a unified approach to the theoretical and experimental study of fluid dynamics in the different frequency-wavelength regions of fluctuations. The next chapter introduces the basic tools used throughout the book: the time correlation functions and their fundamental properties. Emphasis is given to the role of the memory function as the central quantity in interpreting the physical processes and in introducing model calculations for the description of the dynamical behavior of fluid systems. The second part is concerned with the dynamics of selfdiffusion.
The detailed motions of a particle moving in a flu id medium are first treated in terms of the velocity autocorrelation function. Then the extension to include spatial correlation effects is discussed. The third part deals with the dynamics of collective phenomena. Fluctuations at low frequencies and long wavelengths as observed by light scattering spectroscopy are shown
to be well described by hydrodynamic theory. This description is then generalized and extended to the region of molecular frequencies and wavelengths probed by neutron scattering and computer experiments where non local responses in the fluid have to
be accounted for. A major conclusion that emerges from the various analyses and data interpretations presented and discussed
in this book is that as a dynamic medium the fluid goes through two stages of response, a rapid short-time response which depends on the individual events of molecular interactions (collisions) and a slower response generated by the dynamics of interactions among groups of particles. This dual characteristic-time behavior, which is observed in the study of both single-particle motions and collective phenomena,is not completely understood theoretically, nor has it been fully studied experimentally. It will undoubtedly be a primary focus of future investigations in the field of liquid-state dynamics.
For graduate students the book serves as an introduction to the theory of time correlation functions and the molecular theory of fluid dynamics, for experimentalists it provides theoretical tools useful for the analysis of experimental results, for theoreticians it represents a comprehensive source of illustrations of the theories most relevant in practical applications.