A new autonomous memristive megastable oscillator and its Hamiltonian-energy-dependent megastability.

Multistability is a special issue in nonlinear dynamics. In this paper, a three-dimensional autonomous memristive chaotic system is presented, with interesting multiple coexisting attractors in a nested structure observed, which indicates the megastability. Furthermore, the extreme event is investigated by local riddled basins. Based on Helmholtz's theorem, the average Hamiltonian energy with respect to initial-dependent dynamics is calculated and the energy transition explains the occurrence mechanisms of the megastability and the extreme event. Finally, by configuring initial conditions, multiple coexisting megastable attractors are captured in PSIM simulations and FPGA circuits, which validate the numerical results.