Circular motion of charged particles near a charged black hole

We study the circular motion of charged particles near a black hole. The general form Lyapunov exponent is obtained by using Jacobian matrix. results show that chaos bound can be saturated on horizon. By further expanding horizon and investigating Reissner-Nordstr\"om(RN) holes with different $M/Q$, we find in contrast to static equilibrium, have larger due existence angular momentum. For RN which mass-charge ratio $1<M/Q <1.1547$, locally violated null time-like large As an illustration universality our results, particles' Reissner-Nordstr\"om Anti-de Sitter (RN-AdS) hole momentum exceed under background RN-AdS range $1.23132<M/Q<1.75225$.