K-entropy (average Lyapunov exponent), dynamics and chaos for particle trajectories. Molecular dynamics simulation for electron-ion strongly coupled plasmas

Abstract

K-entropy is calculated for strongly coupled plasmas by a molecular dynamics method for both electrons and ions. Various time intervals are considered. The results are obtained for different initial displacements of particles, nonidealty parameters, the ion-electron mass ratios, ion-electron interaction potential and the number of particles. Two different time intervals for the system were investigated. At small times both electron and ion trajectories diverge exponentially with an identical exponent K being the same for different ion-electron mass ratios. Then electron characteristics reach their saturation but ion trajectories continue to diverge with their own exponent dependent on the ion-electron mass ratio. Mass ratios 10-100000 are considered. The K values increase when the electron-ion potential at small distances is changed from mild attraction to strong repulsion. No remarkable dependence is discovered for the particle numbers from 20 to 400.