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Quantumlike short-time behavior of a classical crystal.
Gianluca Marcelli1, Alexander Tenenbaum
1Department of Bioengineering, Physiological Flow Studies Group, Imperial College of Science Technology and Medicine, London SW7 2AZ, United Kingdom.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|December 20, 2003
Summary
This study reveals that the specific heat of crystals depends on observation time, especially at low temperatures. Near-quantum values are observed at short times, diverging from classical predictions.
Area of Science:
- Condensed Matter Physics
- Computational Materials Science
Background:
- Classical physics predicts a constant specific heat (3R) for solids.
- Understanding crystal dynamics and relaxation is crucial for materials science.
Purpose of the Study:
- To investigate the microcanonical equilibrium dynamics of a face-centered-cubic Lennard-Jones crystal.
- To analyze the time-dependent behavior of specific heat in crystals.
Main Methods:
- Molecular-dynamics simulation of a Lennard-Jones crystal.
- Computation of normal modes to study dynamics.
- Analysis of kinetic energy fluctuations and specific heat over time.
Main Results:
- Specific heat shows time-dependent behavior, particularly at low temperatures.
- Short observation times (approx. 20 ps) yield specific heat values closer to quantum predictions.
- Longer observation times approach the classical Dulong-Petit law (3R), except at very low temperatures where it nears zero.
Conclusions:
- The time dependence of crystal specific heat mimics supercooled liquid behavior near glass transitions.
- A new formulation for measuring microcanonical specific heat is necessitated by slow kinetic energy relaxation.