  In atomic, molecular, and nuclear physics, the method of complex coordinate
rotation is a widely used theoretical tool for studying resonant states. Here,
we propose a novel implementation of this method based on the gradient
optimization (CCR-GO). The main strength of the CCR-GO method is that it does
not require manual adjustment of optimization parameters in the wave function;
instead, a mathematically well-defined optimization path can be followed. Our
method is proven to be very efficient in searching resonant positions and
widths over a variety of few-body atomic systems, and can significantly improve
the accuracy of the results. As a special case, the CCR-GO method is equally
capable of dealing with bound-state problems with high accuracy, which is
traditionally achieved through the usual extreme conditions of energy itself.
