Curvature fluctuations and the Lyapunov exponent at melting
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067 (India)
We calculate the maximal Lyapunov exponent in constant-energy molecular-dynamics simulations at the melting transition for finite clusters of 6{endash}13 particles (model rare-gas and metallic systems) as well as for bulk rare-gas solids. For clusters, the Lyapunov exponent generally varies linearly with the total energy, but the {ital slope} changes sharply at the melting transition. In the bulk system, melting corresponds to a jump in the Lyapunov exponent, and this corresponds to a singularity in the variance of the curvature of the potential-energy surface. In these systems there are two mechanisms of chaos{emdash}local instability and parametric instability. We calculate the contribution of the parametric instability toward the chaoticity of these systems using a recently proposed formalism. The contribution of parametric instability is a continuous function of energy in small clusters but not in the bulk where the melting corresponds to a decrease in this quantity. This implies that the melting in small clusters does not lead to enhanced local instability. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 542209
- Journal Information:
- Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, Vol. 56, Issue 3; Other Information: PBD: Sep 1997
- Country of Publication:
- United States
- Language:
- English
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