Molecular dynamics and irreversibility, from Boltzman to Nose
Conference
·
OSTI ID:6343239
Throughout Boltzmann's life-long atomistic study of irreversibility, he emphasized the one-body distribution function f/sub 1/, averaged over many particles, with the underlying dynamics taken to be a series of two-body collisions. His derivation of the H theorem, linking dynamics and thermodynamics, remains the major accomplishment in understanding the Second Law of Thermodynamics. Today his analytic one-body approach has largely been superceded by using fast computers to simulate many-body ''Molecular Dynamics''. Fermi originated Molecular Dynamics at Los Alamos in 1953. His few-body one-dimensional chains launched a generation of numerical studies of Lyapunov-unstable ordinary different equations. By 1972 computers could simulate 1000-body gases, liquids, or solids, and a new nonequilibrium mechanics was developing to facilitate this work. In 1984, Nose made a major contribution. He showed how to introduce macroscopic variables, such as temperature, pressure, and heat flux, directly into time-reversible microscopic equations of motion. When Nose's mechanics is applied to nonequilibrium systems zero-volume ''strange attractors'' form in the many-body phase space. The attractors provide a new explanation for the classical problem of irreversibility that fascinated Boltzmann. Here I trace the evolution of molecular dynamics from Fermi's work at Los Alamos to Nose recent work, and I speculate on the applicability of the new nonequilibrium ideas to quantum systems. 62 refs., 24 figs.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6343239
- Report Number(s):
- UCRL-100259; CONF-890180-1; ON: DE89006740
- Country of Publication:
- United States
- Language:
- English
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