Periodic orbits for three particles with finite angular momentum

We present a novel numerical method to calculate periodic orbits for dynamical systems by an iterative process which is based directly on the action integral in classical mechanics. New solutions are obtained for the planar motion of three equal mass particles on a common periodic orbit with finite total angular momentum, under the action of attractive pairwise forces of the form $1/r^{p+1}$. It is shown that for $-2 < p \le 0$, Lagrange's 1772 circular solution is the limiting case of a complex symmetric orbit. The evolution of this orbit and another recently discovered one in the shape of a figure eight is investigated for a range of angular momenta. Extensions to n equal mass particles and to three particles of different masses are also discussed briefly.