Chaos bound of charged particles around phantom AdS black hole
In this paper, we investigated the chaos of the phantom AdS black hole in near-horizon regions and at a certain distance from the black hole, where the Lyapunov exponent was calculated by the Jacobian determinant. We found that the angular momenta of charged particles nearby the black hole affect the position of the equilibrium orbit as well as the Lyapunov exponent. When the charge is large enough and the angular momenta take particular values, the bound is violated at a certain distance from the event horizon. Concurrently, we compared the differences by analyzing tables and figures after taking different values of $η$, where $η$ is a constant indicating the nature of the electromagnetic field. When $η=1$, it corresponds to the Reissner-Nordstr$\ddot{o}$m-AdS black hole (RN-AdS black hole) and it represents the phantom AdS black hole when $η=-1$. In this way, we can draw the following conclusions. Under different values of $η$, the variation trends of curves related to $λ^{2}-κ^{2}$ could be different, where it can be judged whether the constraint is violated by determining if $λ^{2}-κ^{2}$ is greater than zero. In addition, the corresponding numerical values of angular momenta violating the bound in the phantom AdS black hole are much smaller than the case of RN-AdS black hole. But cases in these different black holes have the same rules to violate the bound. The large absolute values of charge and $Λ$ are more likely to violate the bound.