A mechanism for generation of strong energy fluctuations in one-dimensional systems

A mechanism for the generation of strong energy fluctuations in a chain of harmonically and anharmonically coupled atoms in a state of thermodynamic equilibrium has been investigated by a molecular dynamics method. Energy fluctuations multiply exceeding the mean value were localized in a group of three to five atoms with lifetime on the order of an atomic vibrational period. They arise as a consequence of collisions of density waves propagating along the chain. A collision of waves of the same density sign leads to a fluctuation of the potential energy, while for differing signs a fluctuation in the kinetic energy occurs. In particular, collision of dilitatin waves leads to thermal breaking of the chain. The energy concentration at the moment of collision is 30% greater in a harmonic chain than in an anharmonic one.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 47–52, May, 1991.