The Dynamics of a One-Dimensional Disordered Morse Lattice: Cooling Caused by Adiabatic Stretching

摘要

The dynamics of a disordered one-dimensional lattice of a finite length consisting of N particles interacting according to the Morse potential was studied. Disordering was caused by random interaction potential values between neighboring particles. The dynamics of adiabatic stretching of the Morse lattice was considered in detail. An equation relating temperature to the geometric mean normal vibration frequency, that is, T proportional to (N)root omega(1)omega(2)...omega(N), was obtained in the quasi-harmonic limit. At low temperatures and certain deformation values, strong interaction between modes was observed which resulted in intense energy exchange between them. The reason for this was pair resonances of the n omega(i) = omega(j) type. In addition, there were triple resonances omega(i) + omega(j) = omega(k). Close agreement between analytic results and numerical simulation was obtained. At low specific energy (sic) values, the dynamics of the Morse lattice closely resembled the dynamics of the Fermi-Pasta-Ulam lattice.